Warning fixes

[eriktorbjorn]

This fixes most - not all - of the warnings produced by ZILF 0.9. I think this is a good idea, because otherwise warnings and errors tend to get lost in the noise.

The remaining warnings are:

[warning MDL0417] main.zil:263: ROUTINE: only 3 routine arguments allowed in V3, so last 1 "OPT" argument will never be passed
  in INSERT-FILE called at witness.zil:10
[warning ZIL0202] people.zil:73: mentioned object 'DRIVEWAY-GATE' is never defined
[warning ZIL0502] verbs.zil:493: RETURN value ignored: PROG/REPEAT block is in void context
[warning ZIL0505] people.zil:431: COND: clauses after else part will never be evaluated
[warning ZIL0308] <top level>: too many parts of speech for 'PHONE': Adjective (things.zil:937), Object (things.zil:756), Verb (syntax.zil:99)
[warning ZIL0306] things.zil:937: discarding the Adjective part of speech for 'PHONE'

DRIVEWAY-GATE should probably be DRIVEWAY-ENTRANCE.

[eriktorbjorn]

The COND warning is actually pointing to a bug in the game. See #45