In order to be consistent with the rest of the naming scheme, and in order to avoid conflicts with the higher level rust wrappers, which will be using `Notcurses` for the wrapper struct from now on.
- also deprecate `NotcursesOptions` and rename it to `NcOptions`.
- update examples, docs and readme.
- remove `Nc` & `NcD` wrappers, to move them to notcurses-rs library.
- update the summary header format for Notcurses and NcDirect
- update docs and examples
- add new Notcurses methods: `canhalfblock()` and `canquadrant()`.
- add doc links to NCBLIT_* flags from the capabilities methods.
- update the full-capabilites example to include `canhalfblock`, `canquadrant`,
`canchangecolor` and `canfade` functions.
- rustfmt
- move blitter type, NCBLIT_* constants and NcPixelGeometry from the plane module to the visual module.
- add information about blitter graceful degradation the NcBlitter type.
- add cross linking from/to the NCVISUAL_OPTION_NODEGRADE flag.
- update the full-capabilites example to include braille.
- improve NcVisual.from_rgba documentation.
- fix Notcurses.term_dim_yx documentation.
- new example `poc-planebase` to help find the bug.
- improve full-capabilities example a little.
- refactor Notcurses.palette_size() to return an NcResult.
- refactor & rename example direct-text.rs to direct-capabilities.rs.
- new example full-capabilities.rs
