archive: autodetect archive type by extension (issue2058)

merge with stable

tests: use external coverage, mandate newer version This removes the option for including the stdlib in coverage reports.

churn: use ui.progress instead of --progress

rebase: improve help text - add a paragraph about default dest/source changesets - option help: say "changeset" not "revision" - option help: explain -b/--base better - clarify that -a/--abort and -c/--continue are different from the other options

commands: remove extra indentation from list in help text

server: initialize wsgi app in command, then wrap server around it

server: unnest server classes into module namespace