Tksheet

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`

Fixed:
- Bug with setting header height when header is set to `int`
- Bug with clicking top left rectangle bars to reset header height / index width
- Wrong colors showing when having rows and columns selected at the same time
- Wrong colors showing for particular selection scenarios
- Control select enabled when using `enable_bindings("all")` when it should only be enabled if using `enable_bindings("ctrl_select")`
- When control select was disabled holding control/command would disable basic sheet bindings

Added:
- Add additional binding for `sheet.bind_event()`. `"<<SheetModified>>"` and `"<<SheetRedrawn>>"` are the two existing event options but currently only an empty dict is the associated data

Fixed:
- `disable_bindings()` disable all bindings not disabling edit header/index capability
- Undo not recreating all former selection boxes with cell edits
- Undoing paste where sheet was expanded and rows were hidden didn't remove added rows
- Bug with hidden rows and index highlights
- Bug with hidden rows and text editor newline binding in main table
- Bug with hidden rows and drag and drop rows
- Issue where columns/rows that where selected already would not open dropdown boxes or toggle checkboxes

Removed:
- External function `edit_cell()`, use `open_cell()` and `set_currently_selected()` as alternative

Added:
- Control / Command selecting multiple non-consecutive boxes
- Functions `checkbox_cell`, `checkbox_row`, `checkbox_column`, `checkbox_sheet`, `dropdown_cell`, `dropdown_row`, `dropdown_column`, `dropdown_sheet` and their related deletion functions

Changed:
- `extra_bindings()` undo event type `"insert_row"` renamed `"insert_rows"`, `"insert_col"` renamed `"insert_cols"`
- `extra_bindings()` undo event `.storeddata` has changed for row/column drag drop undo events to `("move_cols" or "move_rows", original_indexes, new_indexes)`
- Initialization argument `max_rh` renamed `max_row_height`
- Initialization argument `max_colwidth` renamed `max_column_width`
- Initialization argument `max_row_width` renamed `max_index_width`
- `header_dropdown_functions`/`index_dropdown_functions`/`dropdown_functions` now return dict
- Rename internal function `create_text_editor()`
- Select all now maintains existing currently selected cell when using Control/Command - a
- Renamed internal functions `check_views()` `check_xview()` `check_yview()`
- Default argument `redraw` changed to `True` for dropdown/checkbox creation functions
- Internal function `open_text_editor()` keyword argument `set_data_on_close` defaulted to `True`
- Merge internal functions `edit_cell_()` and `open_text_editor()`, remove function `edit_cell_()`
- Better graphical indicators for which columns/rows are being moved when dragging and dropping
- Better retainment of selection boxes after undo cell edits