[git]Add alias for rebase, cleaning, and contains

.gitconfig

@@ -28,6 +28,13 @@
     revertpart = reset -p HEAD^
     diffword = diff --color-words=.
     save = stash save -u
+#rebase last N commits
+    rb = "!f() { git rebase -i HEAD~$1; }; f"
+#rebase since branching on branch N
+    rbi = !sh -c \"git rebase -i `git merge-base $1 HEAD`\" -
+    cleanbr = remote prune origin
+    cleanbrshow = remote prune origin --dry-run
+    contains = !sh -c 'git branch -a --contains $1' -
 
 [branch]
     #New branch track remote