modules: initial FIDOMAIL, MSGBASE, MISC, CONFIG

modules: initial FIDOMAIL, MSGBASE, MISC, CONFIG

FIDOMAIL: handles FTN style mail
- read_packet_file:  reads packed message file and parses headers to messages
- read_message:      reads and parses messages, generates mails (see docs/)
- write_packet_file and write_message are stubbed so far

MSGBASE: handles message base
- area_list:             list existing areas
- area_open, area_close: connect/disconnect from area database
- mail_add, mail_remove: add/remove mail from area
- mail_search:           search area for mails

MISC: lots of helper functions
- FTN-CHRS <-> charset map
- read_datestring:       parse different date formats
- date2text / text2date: convert to/from "yyyy-mm-hh"
- time2text / text2time: convert to/from "hh:mm:ss"
- fido2text / text2fido: convert to/from "z:n/n.p"
- netnodelist2text / text2netnodelist: converts parsed PATH/SEEN-BY kludges

CONFIG: configuration store