MDLSITE-2205 cs: allow pure 20-120 comment seps

In order to allow the named "comment-separators":

Every valid (2-slashes+space) comment having at least 10 hyphens will be verified to:
- Have only hyphens.
- Have between 20 and 120 hyphens.
- Not being comment after code.

Any other comment will be processed normally, with general inline comment rules.

Tests added verifying both valid "comment-separators" and invalid ones.

Ciao :-)