Extract text replacement functionality into common library

[rugk]

As said in #4 (comment):

Hmm yeah, maybe it would make sense to make a common library at some point of time. slightly_smiling_face

Reason: It’s also used in rugk/awesome-emoji-picker#93 etc.

@tdulcet you’ve upvoted it, so I guess you agree.
How hard to you think it is?

If it’s easy we can make it before v1.0.

I’d of course would like to put it into https://github.com/TinyWebEx/ then and I could certainly help and setup the repo etc.

[tdulcet]

@tdulcet you’ve upvoted it, so I guess you agree.
How hard to you think it is?

Hmm, well we cannot currently put it into a module because of bug 1451545. However, we could always load it as a separate script in the manifest.json file.

How hard it would be would depend on what exactly we want the library to do. If we just want to put the common getCaretPosition(), insertAtCaret(), insertAndSelect(), insertIntoPage(), countChars(), deleteCaret() and firstDifferenceIndex() functions into the library, that should be very easy. Generalizing the autocorrect() and undoAutocorrect() functions would be more difficult, although similar to what some of your other libraries already do. Note that this would also depend on #37.

[rugk]

Made a repo for that: https://github.com/TinyWebEx/TextModification/