ready for 0.8.2

updated changelog, ready for release

Merge pull request imgui-rs#530 from sanbox-irl/prep-0.8.0

prep 0.8.0

imgui-winit-support release 0.7.1

Merge pull request imgui-rs#440 from sanbox-irl/feat_permissive_dropping

permissive dropping

Release: 0.6.0

Release: 0.5.0

Release: 0.4.0