CELL_ALPHA_OPAQUE et al were defined as 0..3, meaning
CELL_ALPHA_SHIFT had to be used to compare them to their
channel representations. Instead, define them in said
representation outright, eliminating the need to shift while
retaining arithmetic properties, and zero initialization for
CELL_ALPHA_OPAQUE. Eliminate CELL_ALPHA_SHIFT #738.
This is to make it possible, in the future, to create multiple instances
of `NotCurses` for multiple terminals. The first instance of
`NotCurses` becomes the default one, so that any instances of other
classes that aren't explicitly created with a pointer to another
`NotCurses` instance still work as expected.
Note that currently trying to call `notcurses_init` twice results in the
following error for me:
0x55555559bfc0 is already registered for signals
Couldn't drop signals: 0x55555559bfc0 != 0x5555555b6720
terminate called after throwing an instance of 'ncpp::init_error*'
Program received signal SIGABRT, Aborted.
The error is signalled by `setup_signals` and the pointer shown in the
message points to the first `struct notcurses` instance created.
* CMake: add USE_PANDOC, USE_DOXYGEN options #101
* README: mention rust
* start integrating rust into build #101
* CMake: add USE_NETWORK option for cargo
* Debian: build-dep on doxygen
* rust: colloquy checks in Cargo.lock
* extract NCKEY defines into their own include
* colloquy: use clap to parse CLI args
* CMake: unify option namespace
* Python: update include path
* Rust: fix up --frozen workings for -DUSE_NETWORK=off
* CMake: abstract out colloquy a little
* Sync direct.hh to the New Way
