The path package now contains only functions which
deal with slashed paths, sensible for any OS when dealing
with network paths or URLs.  OS-specific functionality
has been moved into the new path/filepath package.

This also includes fixes for godoc, goinstall and other
packages which were mixing slashed and OS-specific paths.

R=rsc, gri, mattn, brainman
CC=golang-dev
https://golang.org/cl/4252044

R=rsc
CC=golang-dev
https://golang.org/cl/4266044

Cgo changed to write these files into _obj, but some
trees may still have the old ones in the source directory.
They need to be removed during make clean so that
a subsequent build will use the ones in _obj.

R=r, r2
CC=golang-dev
https://golang.org/cl/4254056

R=rsc1, mattn, bradfitzwork, pascal, bradfitzgo
CC=golang-dev
https://golang.org/cl/4214042

FreeBSD's execve implementation has an integer underflow in a bounds test which
causes it to erroneously think the argument list is too long when argv[0] is
longer than interpreter + path.

R=rsc, bradfitz, rsc1
CC=golang-dev
https://golang.org/cl/4259056

also fix a caching bug.

R=rsc
CC=golang-dev
https://golang.org/cl/4261049

R=bradfitzgo, bradfitzwork
CC=golang-dev
https://golang.org/cl/4264047

R=golang-dev, bradfitzgo
CC=golang-dev
https://golang.org/cl/4235052

R=dsymonds
CC=golang-dev
https://golang.org/cl/4256053

A change a while back stop sending data for unexported fields
but due to an oversight the type info was being sent also. It's
inconsequential but wrong to do that.

R=rsc, rh
CC=golang-dev
https://golang.org/cl/4252058

R=rh
CC=golang-dev
https://golang.org/cl/4239060

This also breaks fs_test into two parts
as the range tests test http's private httpRange
and I had to change the fs_test package from
"http" to "http_test" to use httptest which otherwise
has a cyclic depedency back on http.

Aside: we should start exposing the Range
stuff in the future.

R=rsc
CC=golang-dev
https://golang.org/cl/4261047

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4243058

R=rsc, bradfitzgo, bradfitzwork
CC=golang-dev
https://golang.org/cl/4266042

Fixes #53.

R=bradfitzgo, bradfitzwork
CC=golang-dev
https://golang.org/cl/4240075

The test was checking for a buffer to be empty but
actually racing with the background goroutine that
was emptying it.  Left a comment so that the check
is not reintroduced later.

Fixes #1557.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4248063

Passing a frame size of 1 was causing the cgo callback
to push 1 byte of arguments onto the stack, making
the stack pointer misaligned, which had the effect of
hiding all the pointers on the stack from the garbage
collector.

SWIG only wraps calls to C++ virtual methods, so it
always has at least 1 argument, so SWIG does not need
to be fixed too.

Fixes #1328.

R=iant
CC=golang-dev
https://golang.org/cl/4261046

R=r
CC=golang-dev
https://golang.org/cl/4266041

R=rsc, r
CC=golang-dev
https://golang.org/cl/4260051

R=rsc
CC=golang-dev
https://golang.org/cl/4259051

These allow data items to control their own representation.

For now, the implementation requires that the value passed
to Encode and Decode must be exactly the type of the
methods' receiver; it cannot be, for instance, T if the receiver
is of type *T.  This will be fixed in a later CL.

R=rsc
CC=golang-dev
https://golang.org/cl/4235051

The tests require Perl, not commonly installed on Windows.

R=rsc, brainman
CC=golang-dev
https://golang.org/cl/4239057

(Shouldn't happen, but if it does, it's useful to be
able to use printf to debug it.)

R=r
CC=golang-dev
https://golang.org/cl/4250057

This allows a data item that can marshal itself to be transmitted by its
own encoding, enabling some types to be handled that cannot be
normally, plus providing a way to use gobs on data with unexported
fields.

In this CL, the necessary methods are protected by leading _, so only
package gob can use the facilities (in its tests, of course); this
code is not ready for real use yet.  I could be talked into enabling
it for experimentation, though.  The main drawback is that the
methods must be implemented by the actual type passed through,
not by an indirection from it.  For instance, if *T implements
GobEncoder, you must send a *T, not a T.  This will be addressed
in due course.

Also there is improved commentary and a couple of unrelated
minor bug fixes.

R=rsc
CC=golang-dev
https://golang.org/cl/4243056

http.Transport looks nicer, and ServerTransport
doesn't make much sense anyway.

R=rsc
CC=golang-dev
https://golang.org/cl/4239056

R=rsc, adg, jnw, bradfitzwork
CC=golang-dev
https://golang.org/cl/4247048

R=rsc
CC=golang-dev
https://golang.org/cl/4264043

R=r, fw, gri, r2, yiyus
CC=golang-dev
https://golang.org/cl/4248051

R=r, rsc, gri
CC=golang-dev
https://golang.org/cl/4257049

R=r, r2
CC=golang-dev
https://golang.org/cl/4252053

R=rsc, iant, r, r2
CC=golang-dev
https://golang.org/cl/4256050

R=golang-dev, rsc, bradfitzwork
CC=golang-dev
https://golang.org/cl/4259048

Currently all http handlers reply to HTTP/1.1 requests with
chunked responses.  This patch allows handlers to opt-out of
that behavior by pre-declaring their Content-Length (which is
then enforced) and unsetting their Transfer-Encoding or
setting it to the "identity" encoding.

R=rsc, bradfitzwork
CC=golang-dev
https://golang.org/cl/4245058

It's a little confusing that os.TempDir and ioutil.TempDir have
different meanings.  I don't know what to change the names to,
if anything.  At least they also have different signatures.

R=golang-dev, bradfitzgo, r, gri
CC=golang-dev
https://golang.org/cl/4247051

R=r, rh, gri, rsc
CC=golang-dev
https://golang.org/cl/4237055

Detect when scan is being called recursively and
re-use the same scan state.

On my machine, for a recursion-heavy benchmark, this
results in 44x speed up. This does impose a 4% penalty
on the non-recursive case, which can be removed by
heap-allocating the saved state, at 40% performance penalty
on the recursive case. Either way is fine with me.

R=r
CC=golang-dev
https://golang.org/cl/4253049

This change makes it possible to take the address of a
struct field or slice element in order to call a method that
requires a pointer receiver.

Existing code that uses the Value.Addr method will have
to change (as gob does in this CL) to call UnsafeAddr instead.

R=r, rog
CC=golang-dev
https://golang.org/cl/4239052

R=ken2
CC=golang-dev
https://golang.org/cl/4245055

TBR=r
CC=golang-dev
https://golang.org/cl/4257054

This borrows a trick from the bzip2 source and effects a decent speed
up when decompressing highly compressed sources. Rather than unshuffle
the BTW block when performing the IBTW, a linked-list is threaded
through the array, in place. This improves cache hit rates.

R=bradfitzgo, bradfitzwork, cw
CC=golang-dev
https://golang.org/cl/4247047