Fix text not being added at caret position

[kittsville]

Text is currently added at the end of the textarea, rather than where the caret (blinking vertical line) is. This makes it harder to use Chomskey for typing large blocks of text and impossible to correctly type combining characters (given #7 is still ongoing).

[kittsville]

Use of insertAtCaret would probably solve this. Its CC By-SA License should be compatible with Chomskey's GPL V2 license as far as I can tell.

[kittsville]

Or maybe it isn't compatible. I hate licensing 😭

[kittsville]

Aw yeah. Plus a chance to work on another repo.

[kittsville]

I won't be pulling this to the live app branch gh-pages until Emre accepts the pull request. Otherwise there might be some issues as I'd be distributing a modified version without stating that the given version is not the original.

If the pull request is accepted then the current code used by Chomskey becomes the original 😀