[FEATURE] Added new methods to Set.
Added new methods to Set:
  clear() - removes all contents.
  delete() - synonym for remove().
  has() - synonym for contains().
  size() - returns count of items in the set.
Add missing semicolons.
Merge pull request #1 from davidderiso/set

[FEATURE] Added new methods to Set.
[DOC] Update docs to reflect changes to set
[DOC] Update package.json to reflect changes to tag
[FEAT] Add gulp to dev dependencies
[REFACTOR] Optimize contains method for tree
[FEATURE] Add Quadtree data structure
[FEATURE] Add Quadtree tests