Add more and better tests for link queries
Implement BETWEEN for link queries
Implement the IN operator for link queries
Add a helper for checking predicate preconditions
Extract some duplicate code for ORing queries
Extract some duplicated query building logic and add support for multi-level link queries
Enable unused parameter warning in the Xcode 6 project
Eliminate more of the differences between link and regular queries
Fix some issues with multilevel link queries

table->link() mutates the table rather than returning a new thing, which
resulted in queries which did not consume the link chain breaking later queries
on the same table.

Searching for "ANY array.col = object" doesn't actually work; it appeared to
work in the tests because was actually searching `array` for an entry with the
same row number as `object`, which coincidentally was the same as the
containing object's row number.
Eliminate some weirdness in add_constraint_to_query
Add better string comparison query tests
Throw an exception if the user asks for case-insensive matching on link queries
Merge pull request #806 from realm/tg-multilevel-link

Extract some duplicated query building logic and add support for multi-level link queries
Merge pull request #795 from realm/tg-link-query

Implement IN and BETWEEN for link queries