Lift in-memory delta tree construction code from svnmucc and drop it into the  Delta Editor -> Ev2 compat shim.
Lift in-memory delta tree construction code from svnmucc and drop it into the 
Delta Editor -> Ev2 compat shim.

This is something of a checkpoint commit.  The code compiles, but doesn't do
much more than that (it isin't even invoked).  This code is still very 
ra session-centric, but will be generalized in a subsequent commit.

* subversion/libsvn_delta/compat.c
  (action_code_t, operation): New types.
  (get_operation, subtract_anchor, build): New.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1173112 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion