Updated the libs. Updated vpc_* to include support for $Conditional in .vgc files. Included vstdlib_exclude.vpc for the OSX builds.
Update text & binary attributes.

This should prevent line ending issues.
Normalize line endings

Fixes issue #75.
Added some more files to .gitignore. Added technical guidelines for pull requests to CONTRIBUTING
Merge https://github.com/ValveSoftware/source-sdk-2013
Merge remote-tracking branch 'source-sdk-2013/master'