Replace GLEW with a glLoadGen loader.

This should fix the GL loading errors that occur in some drivers due to
the use of deprecated functions by GLEW. Side benefits are more accurate
auto-completion (deprecated function and symbols don't exist) and faster
pointer loading (less entrypoints to load). In addition it removes an
external library depency, simplifying the build system a bit and
eliminating one set of binary libraries for Windows.
Update GLFW to 3.0.4 and include x64 lib for MSVC
CMake cleanup

Several cleanups to the buildsystem:
 - Do better factoring of common libs between platforms.
 - Add support to building on Windows.
 - Remove Qt4 support.
 - Re-sort file lists and add missing headers.
Avoid LOGGING redefinition warnings.
Remove hand-crafted Visual Studio solution.
Merge pull request #69 from yuriks/cmake-cleanup

CMake cleanup