MSGID's and FTN MSGID's) so that a bit-mask may be passed to functions like
smb_findhash(), allowing selective duplicate searches without pre-marking
hashes (to be skipped) in a message's hash list. This limits the number of
possible hash sources to 32 total (down from 256) - not a real concern.

This change will render existing msg-id's in hash files obsolete.

The usage of the following functions were effected:
smb_addmsg() - from BOOL (dupechk) to bit-field (dupechk_hashes)
smb_msghashes() - removed dupechk kludge (to pre-mark text hash)
smb_findhash() - added source_mask argument to select which source types