Thanks to `impl From<bool> for Vec2b` one can now shorten some builder
calls, like:
Previous:
```rust
egui::ScrollArea::vertical()
.auto_shrink([false; 2])
```
New:
```rust
egui::ScrollArea::vertical()
.auto_shrink(false)
```
* Move scroll bar spacing settings to a `struct ScrollSpacing`
* Add a demo for changing scroll bar appearance
* Add setting for ScrollBarVisibility in demo
* Add `#[inline]` to a `ScrollArea` builder methods
* Refactor how scroll bar show/hide is computed
* Add support for floating scroll bars
* Tweak color and opacity of the scroll handle
* Allow allocating a fixed size even for floating scroll bars
* Add three pre-sets of scroll bars: solid, thin, floating
* Use floating scroll bars as the default
* Fix id-clash with bidir scroll areas
* Improve demo
* Fix doclink
* Remove reset button from demo
* Fix doclinks
* Fix visual artifact with thin rounded rectangles
* Fix doclink
* typos
* Note the namechange of egui::color to egui::ecolor
* Use a solid triangle for collapsing headers and windows
* Add Shadow::NONE
* Add Visuals::panel_fill, window_fill and window_stroke
* Bug fix: ComboBox::width sets the outer width of the ComboBox
* egui_extras::Table: add functions to access the `Ui` for the header/body
* ComboBox: use solid triangle
* Tweak default menu margin
* Nudge panel separator lines so they stay visible
* Update changelogs
* Nicer debug rectangles
* Move scrollbars into the clip-rect so they are always visible
* Improve table demo
* Add options for controlling inner and outer margin of the scroll bars
* Add line to changelog
* Update egui_extras changelog with recent Table improvements
* Refactor Table:s scroll options
* Add Table::auto_size
* Rename it auto_shrink
* Use simple `ui.interact` for the resize line
* Introduce TableReizeState
* Simplify some code
* Add striped options to table demo
* Auto-size table columns by double-clicking the resize line
* Table: add option to auto-size the columns
* Table: don't let column width gets too small, unless clipping is on
* egui_extras: always use serde
Otherwise using `get_persisted` etc is impossible,
and working around that tedious.
* Avoid clipping last column in a resizable table
* Some better naming
* Table: Use new `Column` for setting column sizes and properties
Also make `clip` a per-column property
* All Table:s store state for auto-sizing purposes
* Customize each column wether or not it is resizable
* fix some auto-sizing bugs
* Fix shrinkage of adaptive column content
* Rename `scroll` to `vscroll` for clarity
* Add Table::scroll_to_row
* scroll_to_row takes alignment
* Fix bug in table sizing
* Strip: turn clipping OFF by default, because it is dangerous and sucks
* Add TableBody::mac_rect helper
* Table: add options to control the scroll area height.
* Docstring fixes
* Cleanup
* egui_extras: Add Table::vertical_scroll_offset
* Added example for TableBuilder::vertical_scroll_offset
* Format code
* Add link to PR in the changelog
Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
