Extend ALTER TABLE DROP PARTITION syntax to use all comparators

Please add SQL support equivalent to drop multiple partitions by operators other than =, basically equivalent of https://issues.apache.org/jira/browse/HIVE-2908

"To drop a partition from a Hive table, this works:

ALTER TABLE foo DROP PARTITION(ds = 'date')

...but it should also work to drop all partitions prior to date.

ALTER TABLE foo DROP PARTITION(ds < 'date')

This task is to implement ALTER TABLE DROP PARTITION for all of the comparators, < > <= >= <> = != instead of just for =."