Clean up visible pages on gui.show.page

[penrods]

• Add remove of delegates on each gui.show.page
• Add ActiveSkillsModel::dump() method
• Add debugging dump for each modification of the active skills
• Filter the messagebus debug dump better
• Add "data:" to the debug message output

[notmart]

hmm, this removes pages on each new one.. which may or may not be what's intended. i tought the idea was more of pushing when a new page arrives..

which to me calls for the need of something more complete, a model based approach for the pages lifecycle (like active skills list) which would then be very finely controllable by the server for which is then possible to easily both have "adding a new gui to the row" "replace everything" "replace only some but not everything" (i guess all the skill writer needs to have would be push_gui() replace_gui())

[notmart]

btw for an idea about that, see the guimodel branch (still very incomplete)

[penrods]

Will integrate with Marcos later work. Closing unmerged.