add rollback support.

Automatically publish on tag.

Add pull and push support for relevant heads. This use pushkey.

Smarter states heads. We use the next relevant heads instead of repo one when asking for the head of a disabled state.

introduce a ``laststatewithout`` method We use it to remove explicite reference to state in to module code. This allow more flexible dev for now.

Autogenerate command table.

add templatekeyword in a proper location

Remove useless comment.

add dedicated command to mark changeset as published or ready This command coul be generated.

reorder extsetup

Get ride of dedicated heads property. This is now handle throught a generic repo.stateheads(state) methode.

rename state related attributes frozen is now published public is now ready

update doc

state are now object.