Suggestion: support for pathlib.Path object

[Magnusm94]

In the __init__ method of configobj.ConfigObj, would it take a lot to be able to accept a pathlib.Path object without causing any other errors? I was testing out by adding a few lines of code above infile = infile or [] at lineno 1192:

if infile and not isinstance(infile, str):
    if type(infile).__base__.__name__ == 'Path':
        infile = str(infile)
infile = infile or []

I'm a bit unsure if this could cause any other issues, or if it works in every case, or if actually importing pathlib.Path would be required if the isinstance() check. Or maybe some other smart way? :)

from pathlib import Path

if isinstance(infile, Path):
    infile = str(infile)
infile = infile or []

[jelmer]

That should work - would you be able to provide a PR with a test?