This change simplifys UI code that uses the Frame type. E.g.:
```rust
fn draw<B: Backend>(frame: &mut Frame<B>) {
// ...
}
```
Frame was generic over Backend because it stored a reference to the
terminal in the field. Instead it now directly stores the viewport area
and current buffer. These are provided at creation time and are valid
for the duration of the frame.
BREAKING CHANGE: Frame is no longer generic over Backend. Code that
accepted `Frame<Backend>` will now need to accept `Frame`. To migrate
existing code, remove any generic parameters from code that uses an
instance of a Frame. E.g. the above code becomes:
```rust
fn draw(frame: &mut Frame) {
// ...
}
```
This helps to keep the prelude small and less likely to conflict with
other crates.
- remove widgets module from prelude as the entire module can be just as
easily imported with `use ratatui::widgets::*;`
- move prelude module into its own file
- update examples to import widgets module instead of just prelude
- added several modules to prelude to make it possible to qualify
imports that collide with other types that have similar names
- merge `Style` and `StyleDiff` together. `Style` now is used to activate or deactivate certain
style rules not to overidden all of them.
- update all impacted widgets, examples and tests.
- Remove deny warnings in lib.rs. This allows easier iteration when developing
new features. The warnings will make the CI fails anyway on the clippy CI
stage.
- Run clippy on all targets (including tests and examples) and all features.
- Fail CI on clippy warnings.
