Update draft release notes for 1.5.6

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

Documentation/RelNotes-1.5.6.txt

@@ -6,37 +6,84 @@ Updates since v1.5.5
 
 (subsystems)
 
+* Comes with updated gitk and git-gui.
 
 (portability)
 
+* git will build on AIX better than before now.
+
+* core.ignorecase configuration variable can be used to work better on
+  filesystems that are not case sensitive.
+
+* "git init" now autodetects the case sensitivity of the filesystem and
+  sets core.ignorecase accordingly.
 
 (performance)
 
+* "git clone" was rewritten in C.  This will hopefully help cloning a
+  repository with insane number of refs.
+
 * "git rebase --onto $there $from $branch" used to switch to the tip of
   $branch only to immediately reset back to $from, smudging work tree
   files unnecessarily.  This has been optimized.
 
+* Object creation codepath in "git-svn" has been optimized by enhancing
+  plumbing commands git-cat-file and git-hash-object.
+
 (usability, bells and whistles)
 
 * "git add -p" (and the "patch" subcommand of "git add -i") can choose to
   apply (or not apply) mode changes independently from contents changes.
 
 * "git bisect help" gives longer and more helpful usage information.
 
+* "git bisect" does not use a special branch "bisect" anymore; instead, it
+  does its work on a detached HEAD.
+
+* "git branch" (and "git checkout -b") can be told to set up
+  branch.<name>.rebase automatically, so that later you can say "git pull"
+  and magically cause "git pull --rebase" to happen.
+
+* "git branch --merged" and "git branch --no-merged" can be used to list
+  branches that have already been merged (or not yet merged) to the
+  current branch.
+
+* "git cherry-pick" and "git revert" can add a sign-off.
+
+* "git commit" mentions the author identity when you are committing
+  somebody else's changes.
+
 * "git diff/log --dirstat" output is consistent between binary and textual
   changes.
 
+* "git filter-branch" rewrites signed tags by demoting them to annotated.
+
+* "git format-patch --no-binary" can produce a patch that lack binary
+  changes (i.e. cannot be used to propagate the whole changes) meant only
+  for reviewing.
+
 * "git gc --auto" honors a new pre-aut-gc hook to temporarily disable it.
 
 * "git log --pretty=tformat:<custom format>" gives a LF after each entry,
   instead of giving a LF between each pair of entries which is how
   "git log --pretty=format:<custom format>" works.
 
+* "git log" and friends learned the "--graph" option to show the ancestry
+  graph at the left margin of the output.
+
+* "git log" and friends can be told to use date format that is different
+  from the default via 'log.date' configuration variable.
+
 * "git send-email" now can send out messages outside a git repository.
 
+* "git send-email --compose" was made aware of rfc2047 quoting.
+
 * "git status" can optionally include output from "git submodule
   summary".
 
+* "git svn" learned --add-author-from option to propagate the authorship
+  by munging the commit log message.
+
 * "gitweb" can read from a system-wide configuration file.
 
 (internal)
@@ -54,6 +101,6 @@ this release, unless otherwise noted.
 
 --
 exec >/var/tmp/1
-O=v1.5.5-56-g5f0734f
+O=v1.5.6-rc0
 echo O=`git describe refs/heads/master`
 git shortlog --no-merges $O..refs/heads/master ^refs/heads/maint