Merge branch 'focus/queries' of https://github.com/DaMSL/K3-Core into focus/queries
Cleaned-up collections library.

Add move constructors, assign operators, insert by move, etc.
This should improve the performance of the collections library in general.

Removed some unnecessary levels of inheritance.
(Using typedefs to preserve legacy code).

Eventually, the generated _Collection classes should inherit directly from a dataspace.

Once we can use higher-order functions that pass-by-reference, the collections library should be fairly tight.
Make examples compile. Remove debug print's