Namespaces should be collapsible in the tag list

[flaimo]

Objects with a lot of tags result in key/value lists that are long and always need to be scrolled to reach certain keys. since more and more tags are used as namespaces, it would be a nice feature that namespaces can be collapsed. i could imagine some sort of arrow symbol left to the keys (like in windows explorer for example), that i can click and tags of a certain namespace get expanded or collapsed. there would be the need for options in the settings, which would allow to define, if namespaces should be expanded or collapsed by default, or if the feature should be deactivated completely (to get the current behavior). also the states for each namespace should be remembered for each object during the run of the program.
an example, where this would be beneficial, would be fuel stations. they have a lot of "fuel:", "payment;", "addr:" and maybe in the future "access:" keys, that would qualify for a collapsed display.