Invalid toggle when caret is after the last or the second-last characters of the selection

[wscourge]

As listed in the known issues, the current behavior is not ideal.

The | represents the current caret position.

There are two problems:

1. Does not work at all when the caret is placed at the end of a string, ie.: "camelCase|"
2. Does not work when the caret is placed after the second-last string's character, ie.: "camelCa|se" (visible on gif)

It happens due to the string length change - it varies between camelCase and snake_case / kebab-case. Caret's position should update in some smart way.

Acceptance criteria:

• Toggling works as expected when the caret is placed at the end of the to-be-toggled string: ie.: camelCase|.
• Toggling works as expected when the caret is placed after the second-last character of the to-be-toggled-string, ie.: camelCas|e.
• The known issues section of the README.md is removed.

I'm open to any suggestions.