Translatable main menu hotkeys.

Hotkeys given in main menu text are now translatable.

Different options for hotkeys can be put inside the hotkey specifier part of the text and it will show the first, but react to all.

previously: `_("H<e>lp")`, 'e', 'E' and '?' hardcoded to select
now: `_("H<e|E|?>lp")`, whatever is between '<', '|' and '>' selects, display is unchanged

related to issue #6645, but doesn't address the other hotkey translation issues.