Fixes#320
Avoid giving "you are back on the bottom" nearly every step when
moving around underwater.
Avoid "you are back on floor" followed by "you trip over <object>"
when fumbling in case that fumbling was due to being on ice when
taking the step to floor. Done for all fumbling rather than just
one-turn fumbling instigated by ice.
When moving from ice or water to ground, show "you are back on floor"
before listing objects at that spot instead of after.
I think there was at least one more thing but have lost track. At
any rate, 'mention_rate' potentially has a new set of bugs.
2e177a7fc4