dynamic UI library

[ColdIV]

waits for #1 to be finished #1 has been resolved!

the elevator has a very simple UI by default, which is ok for most cases, but maybe someone wants more or to build their own interface
to enable that we should:

• move the current UI to a new library (elevator-default-ui ?) Done
• add the library for the default UI to the config and load it via SCM Done
• create a documentation (as part of this repository) on how to create a UI library / how it works Done in default UI library

Update

As I've already resolved most of this issue, the only part that's really left is to optimise it.

Meaning:

• create a (proper?) UI library
• if necessary, rework the current implementation of the UI
  • part of this may include resolving known bugs

Note: I am not too attached to the current UI implementation, if you decide to change a lot, that is fine.

UI libraries should be added at the bottom of the README.md in this repository.

Please keep the documentation up to date, if something changes.

[ChristophLHR]

Will start that one after I am finished with the SCM Script

[ColdIV]

@ChristophLHR I've added the default UI library here.
I've also added minimal instructions. Feel free to add to it or ask if anything is unclear.

Before you work on this issue you should take a look at the known bugs and consider if those could be a problem for the UI development. If that's the case you can either resolve them yourself or tell me to prioritise them.

[ColdIV]

I've also added "UI Libraries" to the elevator README, please add your new library to it when it is finished, for visibility.