cleanup code comments
The comments in the code of the last release are not up-to-date with the
design (for example they still mention the circular buffer, even if that
is not there any more)
The drawings on the wiki pages also need some updating
The comments in the code of the last release are not up-to-date with the
design (for example they still mention the circular buffer, even if that
is not there any more)
The drawings on the wiki pages also need some updating