Minor update of the build system

- Updated the require_all_dependencies function to include
  the *_USE_FILE if a dependency has one.
Implementation of the Qt4-based example harness

- Added the Qt4-based example harness header and source file.
- Updated the cmake build system to detect and use Qt4.
- Minor documentation fix in the other example harnesses.
Merge branch 'feature-qt4-harness' into develop
Multiple fixups

- Fixed a problem in Query::Execution::WaitForResult.
- Fixed an example that used Query::Execution.
- Fixed a problem with mouse motion events in the Qt/GL example harness.
Update to README
Update to README
Multiple changes

- Updated the Qt/GL example harness.
- Minor update in the build system for building tests - added support for Qt/GL.
Misplaced #endif corrected
Find and include OpenGL/gl3.h on OS X when building with OS bundled OpenGL framework
OpenGL 3.2 support: make sure only available sampler types are used
OpenGL 3.2 support: VertexAttribLPointer is only available in OpenGL 4.2
OpenGL 3.2 support: added missing OpenGL 4.x requirements
Search for OpenGL library as well, it finds the right framework on the OS X
OpenGL 3.2 support: GL_PATCHES is only available in OpenGL 4.2
Find and include GLUT framework on OS X
Specify core profile 3.2 on OS X with GLUT to be able to use OpenGL 3.2 features