Add custom chars/letters/symbols

[arnekartveit]

Currently, theres no way to add custom chars/letters/symbols to the app and assign them to the keyboard. This should be a basic functionality and it shouldnt be hard to implement. for all of the nordic users its quite enoying that one cant add æøå to the keyboard. the solution is to use software on the computer or qmk. if added support for uploading custom chars this issue would be solved. :)