Reduce clatter in menus by allowing extra actions on items

[johnd0e]

Implementing actions on longclick/dblclick/contectmenu/etc we could dramatically reduce required menus items number.
Possible reaction on action:

• item toggling/switching between several states (represented by changing text / style / tooltip)
• or dialog for additional setup can be called, eliminating need in separate item in toolbox.

1. Baselayer tiles could be organized in more smart way, e.g. we could mimic stock, where 2 entries cover 4 final variants: Map / *Terrain, and Satellite / *Labels.
   Also:
   • obviously separate light Map/ *Terrain makes sense, with optional style applied (Google basemap with custom styling #126)
   • besides of current Traffic overlay it's possible to add Transit and Bicycle (Dark Google Terrain and other thoughts #199).
   • etc, the same me be applied to any group of tiles by same provider.
   • another example, some tiles may require to setup api key Plugins that require 3rd-party API keys #228
2. Overlays (when using plugins) may occupy a huge space, which could be even hard to scroll.
   • Portals levels are less used but still occupy best place Portals levels in layer chooser #142, levels could be hidden most of time, expanding on longclick.
   • Fly-links, Missions, Player tracker, etc use more that one entry, that could be easy to replace with single.
3. Highlighters often represented by several entries, like "Show visited"/ "Unvisited" Enhance highlighters possibilities #446
4. Plugin toolbox could be cleared from "DrawTools Opts", "Bookmarks Opts", etc: same dialogs'd be called by action in layerChooser Plugins items: tidy up toolbox #347
   Also it is not widely used (though always was possible) to set different actions on click/dblclick/tapthold
5. Android support is possible too. Overlays list already reacts on longclick, toolbox is the same as on desktop (+ panes).
   Some other stuff is not implemented yet, some may be not easily achievable (e.g. not sure if we can change style of labels).