throw exceptions when random iterators are not found for filters.programmable and filters.predicate
fix up exception throwing to actually throw useful exceptions
use BOOST_CHECK_CLOSE so we can get some output when failures happen
beef up error detection in cases where Python array types don't match PDAL dimension types
make filters.mosaic work more better. Provide an example of a mosaic that creates new dimensions, filters data, and updates one leg of the filters.mosaic with Python