__setattr_ and thread._local

(scratch space is pre-allocated stack space since the IC can't
allocate new space itself, in order to have unwinding work)

Allocate a fixed amount (currently: 40 bytes) of extra stack space
in our runtime ics.  This involves changing the function prologue+
epilogue to do more rsp adjustment, and modifying the .eh_frame sections
we generate.

One tricky thing is that we currently use frame pointer elimination
in our runtime ics, but the rest of the scratch space logic had assumed
the scratch would be rbp-relative, which I had to convert to rsp-relative.

This should help with sys_argv breaking.
Hopefully it doesn't introduce too many re-calculations of the
CPython expected output.

In particular, subclassing from (oldstyle_cls, newstyle_cls)
results in a newstyle class, since ClassType.__new__ defers
to any of the bases that are not oldstyle classes.

I think this is ok, but it's implemented pretty differently from CPython
for now so I'm not sure.

hacky (same as the non-iter version) but seems good enough for now

This will prevent tests from dirtying the source/build directories,
or worse overwriting/removing files we care about.

This commit expands on some existing hacks, which I don't like, but
they should hopefully be going away soon.

add cpython buffer + sqlite3 module, and a couple tests.

Implement further changes required for virtualenv

don't assert() if python errors inside of a CFGVisitor's RAII scope

INSTALLING.md: add instructions on getting gdb pretty-printers to work

- make sure that, except for a few special cases, any type which
  has instance attributes gets a __dict__ descriptor
- remove instance attributes from generator and builtin_function_or_method
  objects

- oldstyle classes get a __dict__
- object().__hash__()
- old style classes __getattribute__
- str.splitlines()
- and file(unicode, unicode)
- start_new_thread takes a third argument
- set.union
- instancemethod __getattr__

Fixing makefile link

fixing makefile link

Implement set comprehensions, fix dict comprehension scope

Document that we need libssl-dev