* Rename epaint feature "persistence" to "serialize"
* Add separate "serialize" feature to egui
* egui_demo_lib: separate serialize and persistence features
* Add App::persist_native_window and App::persist_egui_memory
Controls what gets persisted
* Tweak style
More compact, less round, less noisy
* Button text is now same size as body text
* The rounder corners are now less rounded
* Collapsing headers no longer have a frame around them
* Combo-boxes looks better when opened
* Slightly more muted colors
* Remove extra line spacing after `\n` (i.e. between paragraphs)
* Thinner scrollbars
* Tweak light mode
* Tweak shadows
* Fix broken doc link
* Add style tweak to CHANGELOG