This adds some missing result parameters names back to pop_front_safe.
Currently it the procedure won't compile since it's referencing missing variable names.
Adds stem(), short_stem(), and long_ext(); also adds doc-comments to base() and ext().
The 'stem' is usually 'the name' of the file; the basename without the file extension.
To this end, this adds stem(), which is such that:
stem(path) + ext(path) = base(path)
However, 'file extension' has two different meanings to what constitutes it!
> What is the extension of: 'name.tar.gz' ?
Colloquially, you would likely think of it as 'a tarball' - which you might think is '.tar.gz'.
But, if you're writing code to process a file of this type, you would first treat it
as a Gzip file, and then treat the result as a TAR file - i.e: '.gz' ... _followed by_ '.tar'.
ext() returns '.gz' here, since that is the most-immediate format that you would need to use
to decode it; it would be a Gzip stream.
Sometimes though, you do actually want to consider these longer file extensions.
Perhaps you're extracting a tarball, and what to know what to call the intermediate tar file;
perhaps you want to check to see if this file is a tarball, or just a Gzip file;
or maybe you just want 'the name' of the file, and not this "strange 'name-and-part-of-the-extension' thing".
So, this also adds short_stem() and long_ext(), such that:
short_stem(path) + long_ext(path) = base(path)
Thus, we can use either, but the most immediately-useful one is the easiest to reach for:
stem('name.tar.gz') -> 'name.tar'
ext('name.tar.gz') -> '.gz'
short_stem('name.tar.gz') -> 'name'
long_ext('name.tar.gz') -> '.tar.gz'
These procedures are identical to their counterparts when the path only has a simple extension:
stem('name.txt') -> 'name'
ext('name.txt') -> '.txt'
short_stem('name.txt') -> 'name'
long_ext('name.txt') -> '.txt'
