clang-3.7 support

Some small documentation

Not sure how we ended up with the '-1' everywhere.

And also detect attempts to compile on a 32-bit system and
quickly give a nice error message -- fixes #1018.

Changing the INSTALLING instructions. 

Test file for paste (and py.test) modules

Fix build error caused by missing 'override's.

Add a clang libTooling example

Update "roadmap" in readme

Surprisingly hard to get the build to work.  I feel like no one must use
libTooling for out-of-tree projects.  Also, the binary can only be run from
the directory in which it would have been placed for an in-tree project.

It was going to be a refcount discipline checker, but I'm not sure that's
a good use of time right now.  I want to check it in though so that we have it.

- add small 0.5 blurb
- add 0.4 blog post link
- reverse order (latest release first)

microbenchmarks for the presentation

add float_repr_style to sys module and enable test_strtod

Some improvements that let test_fractions could pass.

Add two attribute to str that let test_string pass.

Support CMake 3.3+

I guess our hack for pre-3.3 doesn't work in 3.3, but thankfully
we can include both the pre-3.3 workaround and the actual 3.3+ fix,
and it looks like cmake will end up doing the right thing in both cases.

modified git_svn_gotorev.py to work with both py2 and py3

Changing the INSTALLING instructions. The step Building and testing has broken links to the llvm and clang repository.

Move the sqlalchemy 0.5 test to extra/

Use configurable path to cpython

This removes it from the debug testing configuration and should hopefully
reduce CI timeouts.