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

- Wrapped the call to VertexAttribLPointer into ifdefs. If the function
  is available it is used, otherwise the use of VertexAttribute::Pointer
  with data_type == DataType::Double results in undefined behaviour.
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

- Updated the shapes::Plane shape builder to declare and implement
  the PatchIndices and PatchInstructions only if at least GL 4.2
  API is available.
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
Updated example requirements
Merge branch 'develop' of github.com:matus-chochlik/oglplus into develop