Update Unrar to unrarsrc-5.0.12.tar.gz.
Update Changelog.txt.
Mention Windows 8.1 in the docs.
Update Readme.txt.
Switch back to GCC 4.7.3 due to issues with EMET.
build.bat: allow using /analyze with x64
Disable the C4005 warnings with /analyze.
Put GCCInfo compiled object into the arch-based folders for consistency.