Add support for primary, secondary and middle mouse buttons. Also improve ability to click things in low FPS situations.
This introduces a lot of breaking changes:
Backends/integrations now pass mouse events via the even stream.
Response has an interface of mostly methods instead of public members.
input.mouse is now input.pointer and has new interface.
* Rename 'mouse' to 'pointer' everywhere (pointer = mouse or touch)
* Make Response::clicked and Response::double_clicked into methods
* Remove Response::active and add dragged() and interact_pointer_pos()
* Support multiple mouse buttons
* Make PointerState interface all methods
* Make most members of Response private
* Make `egui_glium::painter::Painter::paint_job` pub
The background is: I'm working on an engine where I would like to draw the gui and the game to the same `glium::Frame`. Haven't found any other obvious, trivial solution. I could of course write my own integration, but I just think this makes sense to be public.
* Make two other necessary functions public
## 0.5.0 - 2020-12-13
### Added ⭐
* Emoji support: 1216 different emojis that work in any text.
* The Demo app comes with a Font Book to explore the available glyphs.
* `ui.horizontal_wrapped(|ui| ...)`: Add widgets on a row but wrap at `max_size`.
* `ui.horizontal_wrapped_for_text`: Like `ui.horizontal_wrapped`, but with spacing made for embedding text.
* `ui.horizontal_for_text`: Like `ui.horizontal`, but with spacing made for embedding text.
* `egui::Layout` now supports justified layouts where contents is _also_ centered, right-aligned, etc.
* `ui.allocate_ui(size, |ui| ...)`: Easily create a child-`Ui` of a given size.
* `SelectableLabel` (`ui.selectable_label` and `ui.selectable_value`): A text-button that can be selected.
* `ui.small_button`: A smaller button that looks good embedded in text.
* `ui.drag_angle_tau`: For those who want to specify angles as fractions of τ (a full turn).
* Add `Resize::id_source` and `ScrollArea::id_source` to let the user avoid Id clashes.
### Changed 🔧
* New default font: [Ubuntu-Light](https://fonts.google.com/specimen/Ubuntu).
* Make it simpler to override fonts in `FontDefinitions`.
* Remove minimum button width.
* Refactor `egui::Layout` substantially, changing its interface.
* Calling `on_hover_text`/`on_hover_ui` multiple times will stack tooltips underneath the previous ones.
* Text wrapping on labels, buttons, checkboxes and radio buttons is now based on the layout.
### Removed 🔥
* Removed the `label!` macro.
