This is just a quick lesson and guide for total newbie coders who want to
"start a MUD", as well as a snippet to make adding new function calls
shorter in general.
If you don't care about the lesson, then I hope the actual tiny bit of code
helps you in your MUD.
Shortens the DECLARE_DO_FUN and DECLARE_SPELL_FUN
calls in interp.h, and magic.h