Unmaintained Mark threads as solved (prefix and optional banners) 1.1.0

It's now possible to move solved threads to other forum nodes.

Forum node restrictions are now possible. The solve/unsolve links will only appear in nodes where the prefix is allowed. Accordingly, the solved banner can only appear in these nodes.

Because the old banner could make sense in prefixless nodes too, there is an new option if it should be only in the prefix'ed nodes or everywhere.