#9 add NOKILLSENT to not use KILLSENT bit

[waldo kitty]

i've added NOKILLSENT to the Notify and Submit options to turn off the KILLSENT bit in makenl generated netmail msgs... by default, the KILLSENT bit is still used so this feature/fix does not alter existing behavoir...

eg:

  Notify errors INTL CRASH NOKILLSENT
  Notify receipt INTL NOKILLSENT
  Notify self INTL
  Submit 1:1/1 INTL CRASH NOKILLSENT

reasoning: some mail tossers will mark the seg file for deletion when they create BSO FLO files from file attach netmail msgs... this causes the segment file to be deleted by the mailer once it is transmitted... this is not always a GoodThing<tm>... this feature/fix allows the operator to specifically not employ the KILLSENT bit so they may retain both the netmail msgs and the segment files if they so desire...

retaining the segment file is important to some operators because they point their makenl directly to the system's netmail area... when makenl generates the file attach netmail msg, it uses the freshly generated segment file in the master directory... when the tosser packs the file attach netmail msg to the destination, it uses the specified segment file from makenl's master directory... this leads to the segment file being deleted from the master directory at the end of the mail session... this feature enables operators to not have to copy the segment files to a temp directory and use a 3rd party tool to send it to their upstream Coordinator... this also allows easier use of the FORCESUBMIT option since the last segment file is still available without some sort of trickery behind the scenes... now makenl can handle these situations naturally as intended without the loss of any files...

files modified:

  config.c   2 lines added, 5 lines changed
  msg.h      1 line added
  msgtool.c  8 lines added, 2 lines changed

the attached patch file was generated against the 3.5.1 code as it existed on 2019-07-29 08:30 -0400...