Add ui.strict config item. This turns off command matching by unambiguous prefix, and is a good thing if you want to write future-proof scripts. This fixes issue 314.

changeset:   0:9426b370c206
tag:         tip
user:        My Name <myname@example.com>
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     commit-1