* Switch the last few remaining icons to true glyphs
(Del/Backspace & Enter).
Also, allow a glyph to be rendered in (fake) bold, and use it for Enter.
* Update fonts
Pickup the tweaked nerdfonts for the backspace symbol
* Add a basic Japanese keyboard layout
Allow for entring Japanese text into text boxes. Only supports kana
and latin letters due to limitations of current VirtualKeyboard
implementation (complex text input with conversion is not possible).
* Allow keyboard layouts to declare custom modifiers
Refactor modifier key setup code and existing keyboard layouts so
that each layout can declare custom modifier key labels. This
allows for greater extensibility and for future keyboard layouts.
