Infer version 0.9.0

This is a source release of Infer packaged with pre-built binaries for clang and facebook-clang-plugins for Linux and MacOS. To use it follow these instructions.

Since the changelog is so big, let's just mention these two items:

• lots of perf improvements and fixes across all analyses (thanks to everyone who reported issues and made pull requests!)
• [experimental] C++ language support. See --cxx in infer --help. This is still in heavy development and only includes a few bug types. Feedback welcome!

The sha256 checksums of the tarballs are:

$ shasum -a 256 -p infer-*-v0.9.0.tar.xz
1596e2d4e67f920349de4950a2b6b98451d5115602826b508eb7b4d8e1b41caf ?infer-linux64-v0.9.0.tar.xz
3aebf37bbcbb3c17912c24bfd1f2aec7b8d1256f0617cca5ddeab7aeab58b3ce ?infer-osx-v0.9.0.tar.xz