* 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
- "Double quotes" for strings (filenames, section names, CLI option arguments, etc)
- 'Single quotes' for characters and CLI option flags
- `Backticks` for keywords and identifiers (symbol names, charmap names, etc)
CLI option flags also have their leading dashes
* 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
These fall into a few categories:
- `_unreachable()`
- Verbose print messages
- Errors that should never practically occur (alloc/read/write failure,
more than UINT32_MAX anonymous labels, etc)
This allows us to control the order in which sections are iterated,
instead of it depending on the internals of `std::map`. (This order
is arbitrary, but should be deterministic regardless.)
- 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
Notable side effects:
* Use the standard-conformant MSVC preproc
* Add test for linker script INCLUDE
* Improve wording of placement conflict errors
* Fix errors from not newline-terminated files
* Teach checkdiff about the linker script doc
* Call linker script "commands" "directives" instead
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Co-authored-by: Rangi42 <remy.oukaour+rangi42@gmail.com>