Move commands.forget over to using new walk code. With no names, it now recursively forgets everything, as is the default behaviour of other commands. And prints the names of all files it hasn't specifically been told to forget.

+ hg init
+ echo This is file a1
+ hg add a
+ hg commit -m 'commit #0' -d '0 0'
+ touch b
+ hg add b
+ rm b
+ hg commit -A '-mcomment #1' -d '0 0'
adding .out
removing b
b never committed!