Installing a callback now returns a CallbackHandle. All map-style APIs
install this handle automatically on the created dynamic, which keeps
the callback installed until the dynamic is freed. All other APIs
return the handle for the caller to either call persist() or store
somewhere.
Now, the dynamic system can be used for application-long data with
almost no fear of leaking data due to how callbacks are being installed.
Technically cycles are still possible by moving clones into the
callbacks, so a WeakDynamic type might be worth exposing.
- Caching font family resolution to avoid scanning the database over and
over. The db should still be cached, but this makes repeated setting
free.
- into_switcher rename for Dynamic<WidgetInstance> to avoid conflicting
with Switchable::switcher()
- Dynamic debugging is less verbose
- IntoDynamic<Validation> for Result<T,E>
- Input no longer blinks cursor when disabled.
This also fixes some inconsistencies that arose when the focus widget
was "stuck" on a removed widget. Button previously handled it hackily in
a redraw function, but now Gooey handles it automatically without
needing to wait for a repaint.
