hgweb: import the whole util module in webcommands instead of just one function This is to allow using other functions from this module easily.

hgweb: add string constants for search mode names It helps detecting mistakes in the mode names.

addremove: don't do full walks Full walks are only necessary when the caller needs the list of clean files. addremove by definition doesn't need them. With this patch and an extension that produces a subset of results for dirstate.walk when full is False, on a repository with over 200,000 files, hg addremove drops from 2.8 seconds to 0.5.

merge with mpm