Slightly tune ptdb parser
educe.ptdb: simplify parser, better Optional use
slightly refactor pdtb parser
Bit of dead-ish code to help parser with regexes

Seems to be slower in practice though
Replace pdtb parser w faster implementation

This one uses funcparserlib.
It needs more helper code, but is a bit cleaner.

(part of it is also slightly cleaner choices which would also
be valid for the pyparsing version)