flush process cache on selection: prompt

git-svn-id: https://svn.r-project.org/ESS/trunk@5512 0bbaf3bd-34e0-0310-bf65-c717079852d4
flush process cache on timer

Needed on user input requests or long operations

git-svn-id: https://svn.r-project.org/ESS/trunk@5513 0bbaf3bd-34e0-0310-bf65-c717079852d4