Tksheet

Fixed:
- Editing header and overflowing text editor so text wraps while using `auto_resize_columns` causes text editor to be out of position
- `insert_columns()` when using an `int` for number of blank columns creates incorrect list layout

Fixed:
- Removed some type hinting that was only available to python versions >= 3.9

Fixed:
- Issues that follow selection boxes being recreated such as resizing columns/rows

Added:
- [180](https://github.com/ragardner/tksheet/issues/180)

Fixed:
- [183](https://github.com/ragardner/tksheet/issues/183)
- [184](https://github.com/ragardner/tksheet/issues/184)

Fixed:
- `extra_bindings()` not binding functions
- [181](https://github.com/ragardner/tksheet/issues/181)