rearranged directory structure:
- main directory is 'Project-O.R.B.S.'
- every project has its own subdirectory
- any files needed, for any project, are in the corresponding
  subdirectories
- there is only one VisualStudio Solution lying in ORBS/

- replaced all #ifdef DEBUG_MODE ... #endif terms by DEBUG_LOG() from
  the log system
added navigation bar in documentation
merged some stuff