Move political parties around

[smashter]

It would be more convenient if instead of copying and pasting policial parties, the number of seats they obtained, and their color into new/different slots in the arch diagram maker that a toggle to move the party ranks up and down on preference could be implemented instead.

[slashme]

Good suggestion, related to #50

[Gouvernathor]

It would even make it obsolete in my view.
And this feature would be just as useful for the Westminster diagram.

[Gouvernathor]

Done on Arch, needs to be done for Westminster as well (and the upcoming Templates too).