drill

73f9827b - DRILL-1470 : cast into varchar should recognize the length parameter in varchar. Fix casting function implementation: the length parameter should mean # of chars, not # of bytes.

DRILL-1470 : cast into varchar should recognize the length parameter in varchar. Fix casting function implementation: the length parameter should mean # of chars, not # of bytes. New unit test case to verify the result from cast function. Fix bug in cast into varchar. When target length = 0, it means we want to keep the input . code clean up. Include change for varbinary cast as well.