ui: use set instead of dict

alias: honor the [defaults] section, fix issue1642

templater: keep a cache of Python functions for filter expressions

templater: replace regex complexity by simple str containment checks

templater: clean up the process method, separating code paths

patchbomb: make diffstat usage clearer Making it clear that diffstat output does not only depend on diffstat being installed - it also needs to be explicitely requested.

patchbomb: describe --attach and --inline options in help

patchbomb: fix help to reflect actual operation In the body, the description is shown in its entirety, unstripped from what was already in the subject.

convert/bzr: warn when source is a lightweight checkout (issue1647)

localrepo: use set instead of dict