0.2 release

bevy_hui 0.2 release for bevy 0.15

https://crates.io/crates/bevy_hui

• added support for overflow_clip_margin
• added scroll to overflow values.
• added new on_changed function binding attribute for all nodes.
  Does nothing by default. Must be triggered by the user. For notifying change in
  custom widgets.
• added shadow_color,shadow_blur,shadow_spread and shadow_offset for the new box shadow.
• added image_region style attribute.

0.1 release

bevy_hui 0.1 release for bevy 0.15

on crates:

https://crates.io/crates/bevy_hui

0.1.0-rc.1

RC for bevy 0.15

MVP

First MVP release, break and leave some issues.