new ess-switch-to-end-of-proc-buffer variable that controls whether C-c C-z
 switches to the end of process buffer. The default is t. You can use prefix
 argument to C-c C-z to toggle this variable.

git-svn-id: https://svn.r-project.org/ESS/trunk@5390 0bbaf3bd-34e0-0310-bf65-c717079852d4