Bug fixes

[dorodnic]

Addressing the following issues:

1. DSO-11755 - Viewer crash when fail to set advanced mode setting
2. Autoexposure 'Mean Intensity Set Point' fixed at 1536 in Viewer #3252 - Cannot change AE mean intensity point in the Viewer
3. DSO-9820 - Cannot load JSON with RGB8 format in the Viewer
4. The tool rs-convert does not terminate its execution #3297 - rs-convert does not terminate execution
5. rs-convert unable to convert to PLY #3214 - rs-convert does not convert to PLY
6. Conditionally define STRINGIFY macro #3159 - conditionally define STRINGIFY macro
7. example.hpp: Where is the namespace rs2 included? #3187 - missing include in example.hpp
8. rs2_depth_frame_get_distance doesn't work for software_device sensor #2844 - rs2_depth_frame_get_distance doesn't work for software_device sensor
9. DSO-11903 - YUY in the Viewer produces white image