Show "Done"/"Never mind" when leaving look modes

Typing quickly when looking can sometimes make it confusing to know
whether or not you're still in look mode, so this should help that.
Fix blessed mapping covering seen mons with objs

This fixes a bug where reading/casting blessed magic mapping would
obscure monsters otherwise in sight with detected objects that they
carried for a turn.  This doesn't happen in UnNetHack for some reason.

This is meant to go with commit 6c9adc7798 (CS989 improve non-cursed
scrolls of magic mapping).

Fixes #72 on GitHub.