Tksheet

Fixed:
- Error with setting/getting header font
- Setting fonts with `set_options()` not working
- Setting fonts after table initialization didn't refresh selection boxes or top left rectangle dimensions

Changed:
- Replaced wildcard imports
- Format code with 120 line length

Fixed:
- Missing imports
- Bug with `delete_rows()`
- Bug with hidden columns, cell options and deleting columns with the inbuilt right click menu
- Bug with a paste that expands the sheet where row lengths are uneven
- Poor box selection for cut and copy with multiple selected boxes
- Bug with `insert_columns()` with uneven row lengths
- Bug with `insert_rows()` if new data contains row lengths that are longer than sheet data
- Errors that occur when dragging and dropping rows/columns beyond the window

Fixed:
- Further potential issues with moving columns where row lengths are uneven
- Potential issues with using `move_rows()` where the provided index is larger than the number of rows
- `dropdown_sheet()` causing error

Fixed:
- [177](https://github.com/ragardner/tksheet/issues/177)

Fixed:
- Error with using `None` to create a dropdown for the entire index when index is not `int`

Fixed:
- Bugs with using `None` to create dropdowns/checkboxes for entire header/index
- Bug with creating dropdowns in row index
- Bug with opening dropdowns in row index
- Bug with `insert_rows()` if `rows` had more columns than existing sheet
- Bug with `delete_column_dropdown()`
- Bug with using external move rows/columns functions where `index_type` wasn't `"displayed"`
- Bug with hidden rows and cutting/copying

Changed:
- Formatted code using `Black`