[MONDRIAN-1776] PhysStatistic.getRelationCardinality() was using an invalid instanceof comparison, checking whether the PhysRelation was of type MondrianDef.Table,
when RolapSchema.PhysTable was intended.  Because of this all cardinality checks would use the stats providers .getQueryCardinality() method for making the determination,
which should be accurate but may be more costly.

This was also causing issues with mongolap since the Mongo dialect does not implement support for .getQueryCardinality().
Merge pull request #221 from mkambol/MONDRIAN-1776

[MONDRIAN-1776] PhysStatistic.getRelationCardinality() was using an inva...