Fix typos.
Merge pull request #11 from waywardmonkeys/typo-fixes

Fix typos.
Create AUTHORS
Update glfw headers and OSX lib
Added StringBuilder::SubstituteAll methods plus test
Added StringBuilder::Contains method and test
Filename upper/lower case fix
Some Linux work (still crashes because required but unsupported GL extensions aren't checked yet
glExt::Discard and IsValid methods
Allow assigning null string pointers to String and StringBuilder
Fixed GL initialization on OSX, apparently it's an error to query the GL_EXTENSIONS string if the Core Profile is used
Fixed broken ShaderTest
Convenience methods in VertexLayout
Additional assert in VertexComponent constructor
Add format printf attribute as applicable.

This will let gcc and clang produce warnings on invalid things
passed for the given format string.
Fix -Wformat warnings.
Made the MeshBuilder interface for adding vertex data more convenient
Add myself to AUTHORs.
Make text match between 2 log statements.
Added a Clear method to MeshBuilder