nhgitset version 4

To update, run "perl DEVEL/nhgitset.pl"

Fixes:
- "nhcommit -a" has been fixed
- NHDT was hardwired in places
- no longer complain about a missing dat directory outside of the
    NetHack source tree
- make update of gitinfo atomic
- Replace some hardwired directory separators with OS-dependent constructs

Backwards Incompatibilities:
- NH_DATESUB's DATE() is now Date() to match the other variables
- MSYS2 requires an additional Perl package - the MSYS2 docs have
    been updated

New Help System:
- git nhhelp
   This command mirrors "git help" for nh* commands.
- See git nhhelp nhsub for general help on substitution variables

New Substitution Variables:
-Brev()
    An aBREViation of $PREFIX-Branch$:$PREFIX-Revision$ - this
    may help get line length under control in file headers.
-Assert(TYPE=VALUE)
    If TYPE does not match VALUE, do not substitute on this line.
    TYPE P checks VALUE against nethack.substprefix
-Project(arg)
    Returns nethack.projectname if there is no arg and an uppercase
    version if arg is uc.

Other New Features:
- Add nethack.projectname
- Documentation updates - see "git nhhelp nhsub"
- On checkout or merge of a branch, check for nhgitset version updates
  and provide an optional message to the user.
- Move NH_DATESUB substitutions here from cron job to keep dates in sync
- PREFIX-* keywords now available in NH_DATESUB templates
- Support use of nhgitset.pl from a different repo; note that update
  checks will be dependent on keeping the original source repo up-to-date
  and in the same location.

DEVEL/VERSION

@@ -0,0 +1,40 @@
+4
+Fixes:
+- "nhcommit -a" has been fixed
+- NHDT was hardwired in places
+- no longer complain about a missing dat directory outside of the
+    NetHack source tree
+- make update of gitinfo atomic
+- Replace some hardwired directory separators with OS-dependent constructs
+
+Backwards Incompatibilities:
+- NH_DATESUB's DATE() is now Date() to match the other variables
+- MSYS2 requires an additional Perl package - the MSYS2 docs have
+    been updated
+
+New Help System:
+- git nhhelp
+   This command mirrors "git help" for nh* commands.
+- See git nhhelp nhsub for general help on substitution variables
+
+New Substitution Variables:
+-Brev()
+    An aBREViation of $PREFIX-Branch$:$PREFIX-Revision$ - this
+    may help get line length under control in file headers.
+-Assert(TYPE=VALUE)
+    If TYPE does not match VALUE, do not substitute on this line.
+    TYPE P checks VALUE against nethack.substprefix
+-Project(arg)
+    Returns nethack.projectname if there is no arg and an uppercase
+    version if arg is uc.
+
+Other New Features:
+- Add nethack.projectname
+- Documentation updates - see "git nhhelp nhsub"
+- On checkout or merge of a branch, check for nhgitset version updates
+- Move NH_DATESUB substitutions here from cron job to keep dates in sync
+- PREFIX-* keywords now available in NH_DATESUB templates
+- Support use of nhgitset.pl from a different repo; note that update
+  checks will be dependent on keeping the original source repo up-to-date
+  and in the same location.
+