Fix natural language description of undirected actions and action effects

[meldckn]

Undirected actions (actions that don’t involve a “second” or “responder” in any conditions or effects) should have custom to-natural-language code instead of reusing the reciprocal/directed action code.

So instead of CHARACTER wants to ACTION with CHARACTER in printed actions,
we should have CHARACTER wants to ACTION.

Same for the text representation of action effects:
CHARACTER is SCHEMATYPE CHARACTER
should be CHARACTER is SCHEMATYPE if the SCHEMATYPE is undirected.

Screenshot from Ishaan Paranjape's driving domain. Thanks Ishaan!