Refactor warnings and errors (#1728)

* 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

include/asm/warning.hpp

@@ -74,4 +74,11 @@ void fatalerror(char const *fmt, ...);
 [[gnu::format(printf, 1, 2)]]
 void error(char const *fmt, ...);
 
+// Used for errors that make it impossible to assemble correctly, but don't
+// affect the following code. The code will fail to assemble but the user will
+// get a list of all errors at the end, making it easier to fix all of them at
+// once.
+[[gnu::format(printf, 1, 2)]]
+void errorNoNewline(char const *fmt, ...);
+
 #endif // RGBDS_ASM_WARNING_HPP