message: Documentation on cmake var VSNRAY_GRAPHICS_API
diff: @@ -34,7 +34,7 @@ Build requirements
  - [NVIDIA CUDA Toolkit][4] version 7.0 or newer (optional)
  - All external dependencies but CMake should be installed as developer packages containing C/C++ header files
  -- In the future we intend to relax the OpenGL and GLEW dependency
  +- The OpenGL and GLEW dependency can optionally be relaxed by setting `VSNRAY_GRAPHICS_AP=None` with CMake
  - When targeting NVIDIA CUDA, make sure you have a C++11 compliant version (v7.0 or newer)
  - Visionaray supports Fermi+ NVIDIA GPUs (e.g. >= GeForce 400 series or >= Quadro {4|5|6}000) (Visionaray does not support texturing on Fermi GPUs, bindless texture support is available with Kepler+ GPUs)
  