Right now, setting up a pathspec to be parsed and processed
requires several data structures and a couple of API calls. This
adds a new high level data structure that contains all the items
that you'll need and high-level APIs that do all of the setup and
all of the teardown. This will make it easier to use pathspecs
in various places with less repeated code.
Instead of returning directly the pattern as the return value, I used an
out parameter, because the function also tests if the passed pathspecs
vector is empty. If yes, it considers that the path "matches", but in
that case there is no matched pattern per se.
There are many scattered functions that look into the contents of
buffers to do various text manipulations (such as escaping or
unescaping data, calculating text stats, guessing if content is
binary, etc). This groups all those functions together into a
new file and converts the code to use that.
This has two enhancements to existing functionality. The old
text stats function is significantly rewritten and the BOM
detection code was extended (although largely we can't deal with
anything other than a UTF8 BOM).
Using the builtin strcmp and strcasecmp as function pointers is
problematic on win32. This adds internal implementations and
divorces us from the platform linkage.
Diff uses a `git_strarray` of path specs to represent a subset
of all files to be processed. It is useful to be able to reuse
this filtering in other places outside diff, so I've moved it
into a standalone set of utilities.
