while here also drops a useless chomp

there's little point to use pledge/unveil and then allow the program to modify itself...

change the mscan format string to siplify the parsing, and refactor the parsing code into the module for reuse. pe is an exception in that it doesn't care about the format string, it just need to decide if the current line starts a new thread or not, that's why it doesn't use the newly introduced `parse'. The new format simplifies pe too though.

otherwise we run with an undef $tid when processing new replies to existing threads.

this wasn't a good idea as the mbox contains sensitive data (IP addresses, hostnames and whatnot). Not good to publish on the web. Reminded by Stefan