When parsing user-provided regex patterns for functions, we must not
fail to provide a diff just because a pattern is not well
formed. Ignore it instead.
Writing a sample Javascript driver pointed out some extra
whitespace handling that needed to be done in the diff driver.
This adds some tests with some sample javascript code that I
pulled off of GitHub just to see what would happen. Also, to
clean up the userdiff test data, I did a "git gc" and packed
up the test objects.
This moves the expected and actual test data along with the source
data for the userdiff tests into the tests/resources/userdiff test
repo and updates the test to use that.
Reorganize the builtin driver table slightly so that core Git
builtin definitions can be imported verbatim. Then take a few of
the core Git drivers and pull them in.
This also creates a test of diffs with the builtin HTML driver
which led to some small error handling fixes in the driver
selection logic.
It's hard or even impossible to correctly free the string buffer
allocated by git_patch_to_str in some circumstances. Drop the function
so people have to use git_patch_to_buf instead - git_buf has a dedicated
destructor.
