REFACTORING: broke instructor-group-related query out of getOtherOfferingsForInstructor() and put it into getOtherOfferingsForInstructorGroup().
refactored internals of getOfferingsForAllInstructorsInSession() action to accomodate for offering model changes.
input escaping to prevent SQL injection.
switched to HEREDOC notation so these queries are more legible. fixed queries while at it.
rewrote queries using JOINS and table aliases.
rolled extra query for session type lookup into a JOIN. also, more death to array_push().
renamed query result variable for consistency reasons.
updated doc blocks.
replaced offering_instructor with offering_x_instructor/offering_x_instructor_group as applicable.