This won't impact Synchronet as it has a separate signal handling
thread, but we still need to behave properly for processes that
don't.  I'm also saying that ENOMEM does not indicate a disconnection,
though it may be better to pretend it was disconnected...

This reverts commit b76f4695.

Incremented the version to 1.72 and date to 2020-03-04 to be up to date with today's release of SlyEdit.

system for v3.17b on Jan-2-2019.

Reverting SlyEdit back to version 1.54, since there seem to still be problems with the new versions that allow text color selection.

Updated the version number & release date in SlyEdit_ReadMe.txt for version 1.58.  Also, updated the SlyEdit DD Message Lister Notes document to mention that my message lister is obsolete in favor of my message reader.