Tksheet

Fixed:
- Rare error when selecting header cell with an empty table and `auto_resize_columns` enabled

Addressed:
- Issue [221](https://github.com/ragardner/tksheet/issues/221)

Fixed:
- Flickering when scrolling by using mouse to drag scroll bars
- Custom bindings overwritten when using `enable_bindings()`
- Rare situation where header/index is temporarily out of sync with table after setting xview/yview

Fixed:
- Potential error caused by moving rows/columns where:
- There exists a header but data is empty
- Data and index/header are all empty but displayed row/column lines exist

Changed:
- Function `equalize_data_row_lengths` parameter `include_header` now `True` by default
- Right clicking with right click select enabled in empty space in the table will now deselect all
- Right clicking on a selected area in the main table will no longer select the cell under the pointer if popup menus are not enabled. Use mouse button 1 to select a cell within a selected area

Added:
- Functions:
- `has_focus()`
- `ctrl_boxes`
- `canvas_boxes`
- `full_move_columns_idxs()`
- `full_move_rows_idxs()`

Fixed:
- Issue with setting sheet xview/yview immediately after initialization
- Visual selection box issue with boxes with 0 length or width

Addressed:
- Issue [220](https://github.com/ragardner/tksheet/issues/220)

Added:
- Functions:
- `boxes` setter for use with `Sheet.get_all_selection_boxes_with_types()` or `Sheet.boxes` property
- `selected` setter
- `all_rows` property to get `all_rows_displayed` `bool`
- `all_columns` property to get `all_columns_displayed` `bool`
- `all_rows` setter to set `all_rows_displayed` `bool`
- `all_columns` setter to set `all_columns_displayed` `bool`
- `displayed_rows` setter uses function `Sheet.display_rows()`
- `displayed_columns` setter uses function `Sheet.display_columns()`

Removed:
- All parameters from function `Sheet.after_redraw()`
- Warnings about version changes from `Sheet()` initialization
- `within_range` parameters from internal `get_selected_cells`/`get_selected_rows`/`get_selected_columns` functions

Fixed:
- Using a cell text editor followed by setting a dropdown box with a text editor would set the previously open cell to the dropdown value

Changed:
- Selection boxes now have rounded corners
- Function `get_checkbox_points` renamed `rounded_box_coords`

Added:
- `rounded_boxes` Sheet option
- WIP `ListBox` class

Fixed:
- Undo error

Added:
- Function `deselect_any()` for non specific selection box type deselections