Add sgcompat files to groupdef.dir

[Former user]

Users of sgcompat are typically the least familiar with how ASSS works, and therefore sgcompat module should have premade groupdef.dir files for the commands it supports.

I propose adding sgcompat_mod, sgcompat_smod, and sgcompat_sysop to groupdef.dir. They would be #included by the standard mod, smod, and sysop groupdef files.

I don't believe that there will be any problems posed by non-sgcompat users, but a double check of the relevant source code is merited.

[Former user]

It looks like there was already support for most of these commands. The missing ones were added in Wiki macro error: Changeset 102fab75c277 not found.