Merge pull request #17 from christiankerl/second_depth_filter_stage

- implemented edge aware filter stage in CpuDepthPacketProcessor
- added configuration options to DepthPacketProcessor interface
added glfw and glew as dependencies; implemented basic opengl window display;
increased opengl version to 3.3
implemented gpu depth processing using opengl shaders
shortened image format definitions
removed opencv dependency from OpenGLDepthPacketProcessor
OpenGLDepthPacketProcessor now uses its configuration