Add FreeBSD 10 support.

This was reported to work by @bthomson in #71.
Closes #71.
Merge pull request #72 from go-gl/feature/freebsd-support

Add FreeBSD 10 support.
Merge branch 'master' into devel_glfw3.1
Go style acronyms.

Closes #74.
Updated readme.
Removed comment

Removed explanation already exists in README
Merge pull request #77 from tapir/devel_glfw3.1

Go style acronyms
Merge pull request #76 from go-gl/support-cb-return-devel

Return previous callbacks
Change macro to compiler flag.
Merge pull request #79 from tapir/master

Change macro to compiler flag.
Fix cflag.
GLFW native handling funcs
Remove space from comment
Merge pull request #80 from go-gl/native-handlers

GLFW native handling funcs
Merge branch 'master' into devel_glfw3.1