Choose your own font and size (#1154)

* Refactor text layout: don't need &Fonts in all functions
* Replace indexing in Fonts with member function
* Wrap Fonts in a Mutex
* Remove mutex for Font::glyph_info_cache
* Remove RwLock around Font::characters
* Put FontsImpl and GalleyCache behind the same Mutex
* Round font sizes to whole pixels before deduplicating them
* Make TextStyle !Copy
* Implement user-named TextStyle:s
* round font size earlier
* Cache fonts based on family and size
* Move TextStyle into egui and Style
* Remove body_text_style
* Query graphics about max texture size and use that as font atlas size
* Recreate texture atlas when it is getting full

egui_demo_lib/src/wrap_app.rs

@@ -190,7 +190,7 @@ impl WrapApp {
                 screen_rect.center(),
                 Align2::CENTER_CENTER,
                 text,
-                TextStyle::Heading,
+                TextStyle::Heading.resolve(&ctx.style()),
                 Color32::WHITE,
             );
         }