Improved the shown error message when a call to the svn client fails
Improved the shown error message when a call to the svn client fails

* trunk/contrib/client-side/emacs/psvn.el:
  (svn-status-1): Fixed a problem in a let binding
  (svn-process-sentinel): Collect multi line error strings
  (svn-handle-error-function): New variable to allow to customize
    the error handling process
  (svn-process-handle-error): Call svn-handle-error-function when it
    is defined


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@874677 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion