Merge pull request #209 from HeroesGrave/master

Share -> Sync
Improve pkg-config error reporting
Merge pull request #210 from gmorenz/master

Improve pkg-config error reporting
Update README for homebrew instructions

Homebrew doesn't contain a glfw3 formula in mainline, it exists in the homebrew/versions tap.
Merge pull request #212 from kballard/patch-1

Update README for homebrew instructions