Release Egui 0.5.0

## 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.

Cargo.lock

@@ -569,7 +569,7 @@ checksum = "9ea835d29036a4087793836fa931b08837ad5e957da9e23886b29586fb9b6650"
 
 [[package]]
 name = "egui"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "ahash",
  "criterion",
@@ -581,7 +581,7 @@ dependencies = [
 
 [[package]]
 name = "egui_glium"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "chrono",
  "clipboard",
@@ -594,7 +594,7 @@ dependencies = [
 
 [[package]]
 name = "egui_web"
-version = "0.4.0"
+version = "0.5.0"
 dependencies = [
  "egui",
  "js-sys",