Addresses https://github.com/wesnoth/wesnoth/issues/9309
when used, the amlas in [unit_type] are replaced by list of amlas in [modify_unit_type],i cannot done add [advancement] without erase amla already present.
GUI2 still does its own handling with double clicks. This doesn't touch that. The default SDL handling is either 500ms (unchanged) or queried from the OS on Windows (an improvement). The click radius defaults to 32, which honestly seems like an acceptable adjustment.
This interface was extremely confusing. pum_info is designed to set `ticks_` only once. This can lead to a situation (exemplified by the music code) where if ticks() is called multiple times in a row, the subsequent times with a counter, that counter would never be incremented since the condition that tests them short circuits on the is-ticks-not-set check.
Also, giving ticks() multiple side effects was very confusing.
These aren't used anymore as of #9332 (save one place, which has been inlined here), and they're not good to rely on, since they don't handle utf8 properly.
This removes `get_teams()`, `get_units()`, and `get_map()` from the display class. These only served as one of the many, many ways to access this data held by the display_context, and that shouldn't be the first-class responsibility of display. Instead, we either access them through the display_context pointer that display holds (whose getter has been renamed to `context()`) or through other more convenient paths (such as play_controller). The editor_display function `map()` has now taken up the mantle of `get_map()`, mostly because both `display::get_map()` and `editor_display::map()` are used, and the former outnumbered the latter.
Removed:
- debug_highlight et al. Unused, and we have the main "display coordinates" debug flag in the base class
- current_team_name. Only used in one place, clearer to just call team_name directly.
- get_terrain_on. Unimplemented
