Attach climb labels to climb object instead of to Labels plugin instance

[foobarbecue]

Better data structure in general is needed here... right now all the labels are stored in an instance of the label plugins, and that includes route labels. This means that climb labels show up in the "labels" menu, which is unnecessary duplication because climbs are already in the "routes / problems" menu. Labels probably needs to be re-named anyway -- they refer to "things that users added to the wall." This issue is vague because it probably implies a huge re-think of how to deal with user-created data... probably let it simmer until some simple server-side stuff is in place.