Moves PC-specific entity and debug menu things to `entity-debug.gc` and
`default-menu-pc.gc` respectively and makes `(declare-file (debug))`
work as it should (no need to wrap the entire file in `(when
*debug-segment*` now!).
Also changes the DGO descriptor format so that it's less verbose. It
might break custom levels, but the format change is very simple so it
should not be difficult for anyone to update to the new format. Sadly,
you lose the completely useless ability to use DGO object names that
don't match the source file name. The horror!
I've also gone ahead and expanded the force envmap option to also force
the ripple effect to be active. I did not notice any performance or
visual drawbacks from this. Gets rid of some distracting LOD and some
water pools appearing super flat (and pitch back for dark eco).
Fixes#1424
