Add a way to ignore line endings when matching lines from --exclude-file

[Jackenmen]

This can be especially when repository is used on Windows with git's core.autocrlf set to true as then some files can have CRLF line endings locally even though they're checked out into git with LF endings. This mixing can therefore cause codespell to not ignore some lines if the line endings in --exclude-file differ from line endings in the file with spelling issue.

[peternewman]

Yeah I'd agree, the line ending should be irrelevant within any of our config files (--exclude-file, --ignore-word-list) etc.

[DimitriPapadopoulos]

I'm reopening this because the new rstrip() from #1889 might remove not only newlines but also spaces. We need to make sure everything works as expected.

[DimitriPapadopoulos]

It seems to be working as expected for me:

$ file exclude-file1.txt exclude-file2.txt test1.txt test2.txt 
exclude-file1.txt: ASCII text
exclude-file2.txt: ASCII text, with CRLF line terminators
test1.txt:         ASCII text
test2.txt:         ASCII text, with CRLF line terminators
$ 
$ codespell test1.txt test2.txt 
test1.txt:1: accepecting ==> accepting
test2.txt:1: accepecting ==> accepting
$ 
$ codespell -x exclude-file1.txt test1.txt test2.txt 
$ 
$ codespell -x exclude-file2.txt test1.txt test2.txt 
$ 

However, the above works whatever spaces we add at the end of any of the above files. It looks like all trailing newlines and spaces are not taken into account when matching lines. Perhaps spaces should be taken into account when matching.

[Jackenmen]

I'm pretty sure that was an intentional choice, trailing space is a nightmare to deal with and requiring that the line in ignore file contains that space doesn't seem to actually benefit you in any way since the contents of the line are still identical.