Strip carriage returns from test (expected) outputs on Windows.

tests/Makefile:
	On Windows, pass --strip-trailing-cr to diff.

README:
src/json.m:
	Don't use `' for single quotes.
Fix quotes in README file.

README:
	As above.
Fix a cut-and-paste error.

src/json.char_buffer.m:
	Delete a comment that was applicable to the CSV reader
	that this file was originally copied from, but is not applicable
	here.