The error handling docs date back to the early error redesign
work and don't match up with the route we actually took. This
brings them in line with actual practice both for external users
and internal implementors, and notes some of the exceptions and
possible bugs.
This implements the loading of regular expression pattern lists
for diff drivers that search for function context in that way.
This also changes the way that diff drivers update options and
interface with xdiff APIs to make them a little more flexible.
This is a significant reorganization of the diff code to break it
into a set of more clearly distinct files and to document the new
organization. Hopefully this will make the diff code easier to
understand and to extend.
This adds a new `git_diff_driver` object that looks of diff driver
information from the attributes and the config so that things like
function content in diff headers can be provided. The full driver
spec is not implemented in the commit - this is focused on the
reorganization of the code and putting the driver hooks in place.
This also removes a few #includes from src/repository.h that were
overbroad, but as a result required extra #includes in a variety
of places since including src/repository.h no longer results in
pulling in the whole world.
This moves a lot of the detailed checkout documentation into a new
file (docs/checkout-internals.md) and simplifies the public docs
for the checkout API.
