Refactored hxlvalidate to use the run() function.
Added first unit test for hxlvalidate.
Added data-type unittest for hxlvalidate -- not working yet.

Added first unit test for hxlmerge
Fix problem with multiple schema loads.
Added Aggregator class to hxlcount, in preparation for supporting
other aggregated values.
Added aggregates to hxlcount.
Bump version for new release.