parse-wormedit: support older wormedit versions

Detect earlier version 95, 94, and 93 headers (or by --version
override), and parse data accordingly (each former format is mostly
a subset; hide output if it's not present yet).

For version 95 there was also an intermediate file in history, which
has been rewritten to specify (sub)version 94 in order to be able to
detect it automatically.

Uses Perl v5.10 features for slightly nicer code (wasn't necessary,
but compatibility is unlikely to be an issue (who else is gonna run
this code anyway?)).