Tksheet

Removed:
- Function `cell_edit_binding()` use `enable_bindings()` instead
- Function `edit_bindings()` use `enable_bindings()` instead

Fixed:
- Error when closing a dropdown in the row index
- Menus modified for every binding for one call of enable/disable bindings with more than one binding
- Editing the index/header cells being allowed when using `enable_bindings("all")`/`enable_bindings()` when it's not supposed to

Changed:
- `Sheet()` initialization parameter `column_width` renamed `default_column_width`
- `set_options()` keyword argument `column_width` renamed `default_column_width`
- `Sheet()` initialization parameter `header_height` renamed `default_header_height`
- `set_options()` keyword argument `header_height` renamed `default_header_height`
- `Sheet()` initialization parameter `row_height` renamed `default_row_height`
- `set_options()` keyword argument `row_height` renamed `default_row_height`
- `Sheet()` initialization parameter `auto_resize_default_row_index` renamed `auto_resize_row_index`
- `set_options()` keyword argument `auto_resize_default_row_index` renamed `auto_resize_row_index`
- `Sheet()` initialization parameter `enable_edit_cell_auto_resize` renamed `cell_auto_resize_enabled`
- `set_options()` keyword argument `enable_edit_cell_auto_resize` renamed `cell_auto_resize_enabled`
- Moved most changable sheet attributes to a dict variable named `ops` (which has dot notation access) accessible from the `Sheet` object
- The order of parameters has been changed for `Sheet()` initialization
- `Sheet` attribute `self.C` renamed `self.PAR`
- Various widget attributes named `self.parentframe` have been renamed `self.PAR`
- Return key on cell editor will move to the next cell regardless of whether the cell was edited
- Parameters for classes `TextEditor`, `TextEditor_`, `Dropdown
- Bindings for cut, copy, paste, delete, undo, redo no longer use both `Command` and `Control` but either one depending on the users operating system
- Internal arrow key binding methodology, if you were previously using this to change the arrow key bindings see [here](https://github.com/ragardner/tksheet/wiki/Version-7#changing-key-bindings) for info on adding arrow key bindings

Added:
- A way to change the in-built popup menu labels, info [here](https://github.com/ragardner/tksheet/wiki/Version-7#sheet-languages-and-bindings)
- A way to change the in-built bindings for cut, copy, paste, delete, undo, redo, select all, all the arrowkey bindings and page up/down, info [here](https://github.com/ragardner/tksheet/wiki/Version-7#changing-key-bindings)

Removed:
- `edit_cell_validation` from `Sheet()` initialization, `set_options()` and everywhere else due to confusion. Use the new function `edit_validation()` instead.
- Functions (use spans instead for the same purpose):
- `header_checkbox`
- `index_checkbox`
- `format_sheet`
- `delete_sheet_format`
- `dropdown_sheet`
- `delete_sheet_dropdown`
- `checkbox_sheet`
- `delete_sheet_checkbox`

- Parameters:
- `verify` from functions `set_column_widths` and `set_row_heights`

- Old unused and deprecated parameters for:
- `get_cell_data()`, `get_sheet_data()`, `get_row_data()`, `get_column_data()`, `yield_sheet_rows()`
- All checkbox and dropdown creation functions

Fixed:
- Grid lines now properly raised above highlighted rows/columns
- Deselect events firing when unnecessary

Changed:
- Using `extra_bindings()` with `"end_edit_cell"`/`"edit_cell"` no longer requires a return value in your bound function to set the cell value to. For end user cell edit validation use the new function `edit_validation()` instead
- Changed functions:
- Parameters and behavior:
- `checkbox` now is used to create checkboxes and utilises spans
- `delete_header_dropdown` default argument changed to required argument and can no longer delete a header wide dropdown
- `delete_index_dropdown` default argument changed to required argument and can no longer delete an index wide dropdown

- Parameters only:
- `move_columns` most parameters changed
- `move_rows` most parameters changed
- `click_checkbox` most parameters changed
- `insert_row` parameter `idx` default argument changed to `None`
- `insert_column` parameter `idx` default argument changed to `None`
- `insert_rows` parameter `idx` default argument changed to `None`
- `insert_columns` parameter `idx` default argument changed to `None`

- Renamed:
- `align` -> `table_align`
- Reorganised order of functions in `sheet.py` to match documentation

Added:
- Method `edit_validation(func: Callable | None = None) -> None` to replace `edit_cell_validation`
- New methods for getting and setting data
- `bind` now also accepts `"<<SheetModified>>"` and `"<<SheetRedrawn>>"` arguments
- Redo, which is enabled when undo is enabled, use by pressing ctrl/cmd + shift + z
- Named spans for sheet options such as highlight, format
- Ctrl/cmd click deselect
- Ability to make currently selected box border different color to selection box border

Other Changes:
- Overhaul and totally change event data sent to functions bound by `extra_bindings()`
- Deselect events are now labelled as "select" events, see the docs on `"selection_boxes"` for more information
- Overhaul internal selection box workings
- Rename tksheet files
- Pressing escape on text editors no longer generates an edit cell/header/index event

Fixed:
- Error with function `set_currently_selected()`

Addressed:
- [207](https://github.com/ragardner/tksheet/issues/207)

Fixed:
- [205](https://github.com/ragardner/tksheet/issues/205)

Improved:
- Term searching improved when typing in a normal state dropdown box

Removed:
- `bind_event()` function, `bind()` to be used instead

Changed:
- tksheet no longer supports Python 3.6, only versions 3.7+

Removed:
Due to errors caused when using Python versions < 3.8 the following functions have been removed:
- __bool__
- __len__

Fixed:
- Sheet init error since version `6.3.0` when running Python 3.7