Merge branch 'sam_1426' into sam_1400
Made validate_pb specially validate VAR terms.
Merge branch 'next' into sam_1400

Conflicts:
	src/rdb_protocol/validate.cc
Fixed typo in comment in datum.hpp.
Fixed expected -> expected_size misnaming in validate.cc.
Merge branch 'sam_1400' into next
Merge branch 'next' into sam_97