submodule: add 'deinit' command

With "git submodule init" the user is able to tell git he cares about one
or more submodules and wants to have it populated on the next call to "git
submodule update". But currently there is no easy way he could tell git he
does not care about a submodule anymore and wants to get rid of his local
work tree (except he knows a lot about submodule internals and removes the
"submodule.$name.url" setting from .git/config together with the work tree
himself).

Help those users by providing a 'deinit' command. This removes the whole
submodule.<name> section from .git/config either for the given
submodule(s) (or for all those which have been initialized if '.' is
given). Fail if the current work tree contains modifications unless
forced. Complain when for a submodule given on the command line the url
setting can't be found in .git/config, but nonetheless don't fail.

Add tests and link the man pages of "git submodule deinit" and "git rm"
to assist the user in deciding whether removing or unregistering the
submodule is the right thing to do for him.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'mn/send-email-authinfo' into pu

Expecting a reroll.
$gmane/215004, $gmane/215024.

* mn/send-email-authinfo:
  git-send-email: add ~/.authinfo parsing
Merge branch 'dg/subtree-fixes' into pu

contrib/subtree updates; there are a few more from T. Zheng that
were posted separately, with an overlap.

Expecting a reroll.

* dg/subtree-fixes:
  contrib/subtree: mkdir the manual directory if needed
  contrib/subtree: honor $(DESTDIR)
  contrib/subtree: fix synopsis and command help
  contrib/subtree: better error handling for "add"
  contrib/subtree: add --unannotate option
  contrib/subtree: use %B for split Subject/Body
  t7900: remove test number comments
Merge branch 'mb/gitweb-highlight-link-target' into pu

Expecting a reroll.
$gmane/211935

* mb/gitweb-highlight-link-target:
  Highlight the link target line in Gitweb using CSS
Merge branch 'mp/diff-algo-config' into pu

Add diff.algorithm configuration so that the user does not type
"diff --histogram".

Looking better; may want tests to protect it from future breakages,
but otherwise it looks ready for 'next'.

Expecting a follow-up to add tests.

* mp/diff-algo-config:
  diff: Introduce --diff-algorithm command line option
  config: Introduce diff.algorithm variable
  git-completion.bash: Autocomplete --minimal and --histogram for git-diff

Conflicts:
	Documentation/diff-config.txt
Merge branch 'mb/remote-default-nn-origin' into pu

When the user does not specify what remote to interact with, we
often attempt to use 'origin'.  This can now be customized via a
configuration variable.

Expecting a reroll.
$gmane/210151

"The first remote becomes the default" bit is better done as a
separate step.

* mb/remote-default-nn-origin:
  Teach get_default_remote to respect remote.default.
  Test that plain "git fetch" uses remote.default when on a detached HEAD.
  Teach clone to set remote.default.
  Teach "git remote" about remote.default.
  Teach remote.c about the remote.default configuration setting.
  Rename remote.c's default_remote_name static variables.

Conflicts:
	builtin/remote.c
	t/t5505-remote.sh
Merge branch 'rc/maint-complete-git-p4' into pu

Comment from Pete will need to be addressed ($gmane/206172).

* rc/maint-complete-git-p4:
  Teach git-completion about git p4
Merge branch 'jc/xprm-generation' into pu

A toy to analyze how bad the clock skews are in histories of real
world projects.

Stalled mostly due to lack of responses.

* jc/xprm-generation:
  test-generation: compute generation numbers and clock skews
Merge branch 'jc/maint-name-rev' into pu

"git name-rev" names the given revision based on a ref that can be
reached in the smallest number of steps from the rev, but that is
not useful when the caller wants to know which tag is the oldest one
that contains the rev.  This teaches a new mode to the command that
uses the oldest ref among those which contain the rev.

I am not sure if this is worth it; for one thing, even with the help
from notes-cache, it seems to make the "describe --contains" even
slower. Also the command will be unusably slow for a user who does
not have a write access (hence unable to create or update the
notes-cache).

Stalled mostly due to lack of responses.

* jc/maint-name-rev:
  describe --contains: use "name-rev --algorithm=weight"
  name-rev --algorithm=weight: tests and documentation
  name-rev --algorithm=weight: cache the computed weight in notes
  name-rev --algorithm=weight: trivial optimization
  name-rev: --algorithm option
  name_rev: clarify the logic to assign a new tip-name to a commit
  name-rev: lose unnecessary typedef

Conflicts:
	builtin/name-rev.c
Merge branch 'jk/lua-hackery' into pu

Interesting exercise. When we do this for real, we probably would want
to wrap a commit to make it more like an "object" with methods like
"parents", etc.

* jk/lua-hackery:
  pretty: fix up one-off format_commit_message calls
  Minimum compilation fixup
  Makefile: make "lua" a bit more configurable
  add a "lua" pretty format
  add basic lua infrastructure
  pretty: make some commit-parsing helpers more public
Merge branch 'jl/submodule-deinit' into pu

# By Jens Lehmann
* jl/submodule-deinit:
  submodule: add 'deinit' command

Conflicts:
	Documentation/git-submodule.txt
	git-submodule.sh
Merge branch 'jc/add-delete-default' into pu

"git add dir/" updated modified files and added new files, but does
not notice removed files, which may be "Huh?" to some users.  They
can of course use "git add -A dir/", but why should they?

Resurrected from graveyard, as I thought it was a worthwhile thing
to do in the longer term.

Stalled mostly due to lack of responses.

* jc/add-delete-default:
  git add: notice removal of tracked paths by default