Concur

* [x] New windows are now fixed size on creation, if they aren't in imgui.ini. Previously, they were fit to contents, which works OK only when the contents do not fit to window. In the common case of a window containing only an image widget, the window would have been created outright tiny. This could lead to user not even noticing it.
* [x] Add:
* widget `tree_node`
* widget `input_text_multiline`
* widget `text_wrapped`
* scatter square markers (`'s'`)

**Breaking Changes**

* Change colored widgets `text_colored` and `color_button` to use the same color spec as the draw functions.
* Rename `key_pressed` to `key_press`
* Remove `TF.hovered`. Left mouse click & drag is now handled by the `pan_zoom` object.
* Add left mouse interaction support to `image` and `frame`. New arguments `drag_tag` and `down_tag`, and `hover_tag`.
- `pan_zoom.is_hovered` is no longer present.
- `image` event handling was substantially reworked. Starting the drag outside image window no longer triggers panning.
* `key_press` now respects local keyboard layout

**Other changes**

* add `TF.inv_transform` to tranasform from screen-space to content-space
* Make `scatter` also work with empty one-dimensional arrays
* Add an `invisible_button`, and an `image_button`
* Add `selectable` text
* Enable empty polylines
* Add `drag_int2`, `drag_int3`, and `drag_int4` widgets
* Add modifier key support to `key_press`
* Add `main_menu_bar`, `menu`, and `menu_item`

* Fix a bug where long polylines were sometimes corrupted (use-after-free).

* Move the documentation and homepage to a [separate repository](https://github.com/potocpav/python-concur-docs)

* Implement the square marker `'.'` for scatter plot.
* Implement `draw.polygon` and `draw.polygons` - filled convex polygons.

* Add `concur.widgets.mouse_click` widget, which returns mouse position on click
* Add `c.quick_*` functions for quick asynchronous plotting without worrying about the threading and event details
* Add a `fps` argument to `c.main`
- this is breaking if screencast arguments were used positionally.
* Flexible [color specification](https://potocpav.github.io/python-concur-docs/master/draw.html) including [xkcd strings](https://xkcd.com/color/rgb/). Colors like `(0,1,1)`, `'dark red'`, `('blue', 0.5)`, or `0xffaa0000` are now possible.