[PATCH 0/6] External diff interface for diff-cache and friends.

As discussed earlier, I am sending a series of patches to take
advantage of the simplified external diff interface you have
already merged.  This series consists of the following:

[PATCH 1/6] Reworked external diff interface.

    This patch introduces three public functions for diff-cache
    and friends can use to call out to the GIT_EXTERNAL_DIFF
    program when they wish to.  A normal "add/remove/change"
    entry is turned into 7-parameter process invocation of
    GIT_EXTERNAL_DIFF program as before.  In addition, the
    program can now be called with a single parameter when
    diff-cache and friends want to report an unmerged path.

[PATCH 2/6] Reactivate show-diff patch generation

    This patch uses the reworked diff interface to generate
    patches directly out of show-diff when -p is specified.

[PATCH 3/6] Add -p (patch) to diff-tree.

    This patch uses the reworked diff interface to generate
    patches directly out of diff-tree when -p is specified.

[PATCH 4/6] Add -p (patch) to diff-cache.

    This patch uses the reworked diff interface to generate
    patches directly out of diff-cache when -p is specified.

[PATCH 5/6] Teach diff-tree-helper to handle unmerged paths.

    This patch teaches diff-tree-helper to call diff_unmreged()
    so that it can report unmerged paths to GIT_EXTERNAL_DIFF.

[PATCH 6/6] Alternative patch to diff-cache.c

    This is a replacement of PATCH 4, in case you have already
    applied the "non-cached still looks only at cache" fix I
    sent you earlier.  If you took it, PATCH 4 may not apply
    cleanly, in which case this should be easier to work with.