Add "reformat" comand to accept parameter style

[dnedelchev]

I mean the following command format:

trac-admin <ENV> ticket_changesets reformat {stile}

Parameter stile should be optional and the dafault should be "own_stile":

trac-admin /path/to/trac/env ticket_changesets reformat

i.e. this should do the same as the above:

trac-admin /path/to/trac/env ticket_changesets reformat own_stile

and this actually is the new functionality I propose to be actually added:

trac-admin /path/to/trac/env ticket_changesets reformat tracopt_stile

It will in fact allow "undoing" the reformat and also could be used if anyone for any reason wants to uninstall the TracTicketChangesetsPlugin.
I think uninstall is a must-have functionality for any good-quality software by definition.

[mrelbe]

Good point, I will consider this.