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/hooksdir/NHadd

@@ -12,11 +12,32 @@ die "Bad subcommand '$ARGV[0]'" unless $ok{$ARGV[0]};
 # we won't fail on a failure, so just system()
 $rv = system('.git/hooks/nhsub',"--$ARGV[0]",@ARGV[1..$#ARGV]);
 if($rv){
-        print "warning: nhsub failed: $rv $!\n";
+    print "warning: nhsub failed: $rv $!\n";
 }
 
 if(length $ENV{GIT_PREFIX}){
-        chdir($ENV{GIT_PREFIX}) or die "Can't chdir $ENV{GIT_PREFIX}: $!";
+    chdir($ENV{GIT_PREFIX}) or die "Can't chdir $ENV{GIT_PREFIX}: $!";
 }
 
 exec "git", @ARGV or die "Can't exec git: $!";
+
+__END__
+=for nhgitset nhadd Add file contents to the index with NetHack additions
+=for nhgitset nhcommit Record changes to the repository with NetHack additions
+
+=head1 NAME
+
+C<NHadd> - NetHack internal common code for nhadd and nhcommit
+
+=head1 SYNOPSIS
+
+C<git nhadd E<lt>git add optionsE<gt>>
+
+C<git nhcommit E<lt>git add optionsE<gt>>
+
+=head1 DESCRIPTION
+
+Run nhsub with the given arguments, then run C<git add> or C<git commit>
+with the given arguments.  Note that only basic arguments for those commands
+are understood; more complex situations may be handled by running C<git nhsub>
+manually before running C<git add> or C<git commit>.