Various engine fixes/updates

- Set default values for world.dat so it can be created with new()
- Add `r0 to start of the default more string
- Create the world file if it doesn't exist (for globals)
- Fix stupid error in @do trim
- Support all the different @clear commands
- Support the different @key commands properly
- Support @name command
- Only @say is still required for the NPC "stuff" that nothing uses
- Fix blank line skip looking for @begin after @if...then do
  Was looking for comments starting with ; only
- Add try/catch around maint call in case it doesn't exist
- Don't load rules.ref if there's a REF passed on command-line