Initial (Linux-only) support to build GLFW as a CMake's "ExternalProject_add" target.
Update README.md

Improved doc about GLFW.
Linked more required libs on Mac.
Update key mapping for GLFW3
Enabled CMake's "ExternalProject" feature on Windows.
Merge pull request #2 from jcmonnin/fix-key-mapping

Update key mapping for GLFW3
Merge branch 'glfw-cmake-external-project' of https://github.com/zuck/Horde3D into glfw-cmake-external-project
Removed debug message.
CMake's "ExternalProject" support for Mac.
Increased minimum required CMake's version to 2.8.
Fixed window title handing in samples.