Create new wrapping types that can safely encapsulate the mutable references,
and implement Drop and automatic (de)referencing.
- Notcurses
- rename Notcurses* to NcNotcurses*.
- rename NotcursesOptions to NcNotcursesOptions.
- new Notcurses struct.
- implement Drop, AsRef, AsMut, Deref & DerefMut.
- override stop method to be no-op.
- reimplement constructors and associated methods.
- remove without_altscreen_with_banners constructor.
- update examples and tests.
- rustfmt.
- change Option return type for NcResult when appropriate.
- make NcDirect constructors return NcResult.
- rename NcError::new() to with_msg() and simplify new().
- refactor examples:
- rename direct-image.rs to direct-image-c.rs
- recreate using rust methods, as direct-image-rust.rs
- differentiate more throughly between both styles.
- remove the sys namespace on both examples.
