Fix 'tuple index out of range' and other regex grouping issues introduced by commit b1895b6e07edd52e0b0aafea76025e5e064ecc80
Refine debug output a bit
Reformat too-long code line
Patterns: misc. additions, corrections, reformats, etc.
This recursion counter isn't actually used!
Periodically clean up no-longer-needed entries from last replies/repeat-avoidance memory
Prevent very rare occasions where nikkybot doesn't respond at all (because of null response strings accidentally leaking through) and try to catch any remaining causes of this bug