* Use clang-tidy `misc-include-cleaner` for IWYU `#include` cleanup
* Use `std::optional<size_t>` instead of `ssize_t`
* Rename some functions in linkdefs.hpp
* Fix header order
* Remove `err` and `warn`, keep `errx` and `warnx`, using them in RGBGFX too
* Separate RGBGFX and RGBLINK warnings/errors from main options
* Separate `report` function into `error` and `fatal` messages
* Implicit newlines for most RGBASM errors
- The '#' component for type 's' now escapes the string characters
- The '#' component for type 'f' now prints a precision suffix
- The new 'q' component specifies a precision value
- Fixed-point formulas are implemented using IEEE-754 floating-point
internally, which could give infinity or NaN values whose conversion
to fixed-point integer was platform-dependent.
- Formatting fixed-point $8000_0000 (INT32_MIN, -2147483648) was
not putting the negative sign in front.
- Since we have style rules to include foo.hpp at the top of its
corresponding foo.cpp, this takes any headers included by foo.hpp
as being also guaranteed for foo.cpp.
- Use C-style <foo.h> instead of <cfoo>, since the latter only
guarantees putting symbols in the `std` namespace, which we are
not using for C functions (e.g. `printf` not `std::printf`).
- Remove now-unused `__PRETTY_FUNCTION__` reporting
