Insert non emoji unicode using emoji picker

[freemin7]

The emoji picker as is also supplied by most keyboards. Given the more technical audience of Matrix i want to express interest for inserting (customizable) non emoji unicodes.

This could be convenient for math, computer science ...
If the option to add custom character drawers is added it would be nice to support strings of arbitrary length (or long length) not just a single multi-byte character. I could see that being useful for many. Display text vs inserted text should be separately configurable then to not have very large buttons if a longer text is preferred.

One additional bells and whistles would be to allow customisation per conversation.