merged asterix_lsm_stabilization_interval_leftover back: now asterix supporting interval functions over existing temporal types (date, time, and datetime); also accessor functions for the starting and ending of an interval are added. 

git-svn-id: https://asterixdb.googlecode.com/svn/branches/asterix_lsm_stabilization@1699 eaa15691-b419-025a-1212-ee371bd00084