- remove _IO_FILE import and usage.
- create handy constructors for NcDirect & Notcurses.
(but can't implement destructors for copy types…).
- when possible substitute mutable pointers `*mut` for mutable references `&mut`
with associated lifetimes.
- new widgets module, starting with NcReader & NcReaderOptions constructors
- rename EGC to Egc, EGCBackstop to EgcBackstop and ChannelPair to Channels.
- make the original type aliased structs non-public (e.g. ncdirect, ncalign…)
- fix and improve documentation for several types.
- revert renaming crate to nc on use.
- directly import the used types at the beginning of the module.
Now the rustdoc generated documentation is much cleaner.
