✨ Improved Formatting functionality

[EvanZhouDev]

Fixed executing any of the formatting options on a blank selection.

Original Behavior: Injected prefix, and suffix, and selected the prefix and suffix (with nothing in the middle!)
Expected/New Behavior: Injects prefix and suffix before and after your mouse cursor.

Fixed focus after formatting

Original Behavior: Whenever any of the format buttons are pressed, the formatting is finished, but the focus is transferred onto the format button.
Expected/New Behavior: Whenever any of the format buttons are pressed, the formatting is finished, focus should be restored to the textbox. When the selection is empty, the cursor is simply moved between prefix and suffix. When selection is not empty, the formatted section is still selected, but also focused, as per standard text editors.

This PR fixes the issue presented in #83, as well as some additional things that I felt were related.

[EvanZhouDev]

I will reopen this later, I am fixing a few things.