POSIX leaves undefined the order of output if stderr is injected into stdout,
and in practice it differs on Windows (Linux buffers both streams separately,
Windows interleaves them as they arrive without buffering).
This should help testing on other platforms
The old error stack was fairly obtuse and hard to use for debugging.
This improves it notably by ensuring all line numbers are relative
to the file, and not, say, the macro definition.
This is a breaking change if you were parsing the old stack, but
the change should be painless, and the new stack only brings more info.
The syntax is unchanged for files, macros see their name prefixed
with the file they're defined in and a pair of colors, REPT blocks
simply append a '::REPT~n' to the context they're in, where 'n' is
the number of iterations the REPT has done.
This is especially helpful in macro-heavy code such as rgbds-structs.
If a line ended with a string's closing quote, or a newline escape, then
skipping over that line via IF/ELIF/ELSE would fail to count that line,
offsetting the rest of the file.
I have no idea why but for some reason 9829be1 changed *specifically*
`if_skip_to_else` to have incorrect behavior on string endings. The incorrect
behavior on newline escapes seems to have been here since the beginning.
Also added a test to check for both of those behaviors in both functions.
Honestly, it baffles me that nobody ever noticed. I didn't until I started
working on #395.
This adds two new directives: newcharmap and setcharmap.
newcharmap creates a new charmap and switches to it.
setcharmap switches to an existing charmap.
