[Moth-doc] Added Moth documentation.

Commit history:

- Added initial documentation for Moth Processor;
- Added and explained layers functions prototypes;
- Renamed and added content to viewpoint section;
- Added some topics for the sections. Added gifs to examples. Created developer section;
- Added screen positioning concepts and related functions;
- Finished screen positioning concepts section;
- Changed some image extensions from png to jpeg that is less heavy;
- Updated developer section with moth processor internal structure and threads;
- Updated developer section;
- Added minor modification;
- Created style sheet.