Teach git-diff and friends a new format for displaying the difference
of a submodule. The new format is an inline diff of the contents of the
submodule between the commit range of the update. This allows the user
to see the actual code change caused by a submodule update.

Add tests for the new format and option.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Add an extension to git-diff and git-log (and any other graph-aware
displayable output) such that "--line-prefix=<string>" will print the
additional line-prefix on every line of output.

To make this work, we have to fix a few bugs in the graph API that force
graph_show_commit_msg to be used only when you have a valid graph.
Additionally, we extend the default_diff_output_prefix handler to work
even when no graph is enabled.

This is somewhat of a hack on top of the graph API, but I think it
should be acceptable here.

This will be used by a future extension of submodule display which
displays the submodule diff as the actual diff between the pre and post
commit in the submodule project.

Add some tests for both git-log and git-diff to ensure that the prefix
is honored correctly.

Signed-off-by: Jacob Keller <jacob.keller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

* maint:
  Yet another batch for 2.9.3

Signed-off-by: Junio C Hamano <gitster@pobox.com>

"git format-patch" learned format.from configuration variable to
specify the default settings for its "--from" option.

* jt/format-patch-from-config:
  format-patch: format.from gives the default for --from

"git push --force-with-lease" already had enough logic to allow
ensuring that such a push results in creation of a ref (i.e. the
receiving end did not have another push from sideways that would be
discarded by our force-pushing), but didn't expose this possibility
to the users.  It does so now.

* jk/push-force-with-lease-creation:
  t5533: make it pass on case-sensitive filesystems
  push: allow pushing new branches with --force-with-lease
  push: add shorthand for --force-with-lease branch creation
  Documentation/git-push: fix placeholder formatting

Signed-off-by: Junio C Hamano <gitster@pobox.com>

A minor documentation update.

This was split out from a stalled jh/clean-smudge-annex topic
before discarding it.

* jh/clean-smudge-f-doc:
  clarify %f documentation

The API documentation for hashmap was unclear if hashmap_entry
can be safely discarded without any other consideration.  State
that it is safe to do so.

* jc/hashmap-doc-init:
  hashmap: clarify that hashmap_entry can safely be discarded

* maint:
  Hopefully final batch for 2.9.3