Merge pull request #1 from bjz/master

Add upstream modifications.
Fixes to work with the new TLS api.

TLS keys are no longer functions but static variables.
TLS-related functions are no longer unsafe =)
Merge pull request #21 from sebcrozet/master

Fix TLS keys and safetyness.
Add kiss3d to the list of projects using glfw-rs
Merge branch 'master' of git://github.com/bjz/glfw-rs