Added generic scalar aggregate function that wraps around existing non-scalar aggregate functions (this way we should be able to easily add scalar versions of all agg funcs). Implemented scalar count using it.

git-svn-id: https://asterixdb.googlecode.com/svn/branches/asterix_fix_agg@577 eaa15691-b419-025a-1212-ee371bd00084
7 files changed