New version with keyboard and more coordinate systems

[kaltokri]

I've added the keyboard from the dcs forum and added more coordinate systems for using scratchpad with A-10C.

[rkusa]

Thanks for proposing these improvements! Before I dive into a code-review I see two points that need to be discussed:

• As I understand it, you are not the author of the keyboard code, so unless the author in the forum did license the code, we cannot simply add it here I am afraid
• Feature Request: Add the keyboard and more details for +L/L #13 still has open points for discussion, e.g. whether the keyboard should be disabled by default (enabled via config)

[rkusa]

I made up my mind how I think the keyboard can be integrated. I don't want the keyboard in this repo. It's just something I don't need and thus don't want to maintain. Instead, I'd rather expose parts of the Scratchpad into the global scope of the hooks environment. This can be event handlers (like onShow, onHide, onMove) and methods to get access to the underlying textarea. The keyboard could then be a separate mod (hook script) that acts as a plugin to the scratchpad. I'd be happy to accept PRs that add the methods/event handlers necessary to make that happen, but I'll close this PR here. I still appreciate the effort you put into the PR!

[rkusa]

I've started a prototype to make it easier to create extensions to the Scratchpad #35. This makes it fairly straightforward to create a keyboard. If I end up adding this extensions feature, I'll be accepting community extensions into this repo. They will just not be included in the default-installation and they will rely on community contributions for maintanance.

[DOWTarget]

I need a Keyboard, amd i'm very happy for this improvement