Reduce Garbage: Each use of concat creates a new array, so avoid using it inside HashMap.search()
Modify coordinate hash to use bit shifting instead of string concat.  Will only work with 16bit coordinates now.
Reduce Garbage: don't create a new object every time HashMap.key is called
Create a special .refresh() function to update an objects position, rather than removing and adding it again.
Garbage Reduce: use existing _mbr object in HashMap.key instead of creating one with mbr()
Merge pull request #430 from starwed/hashmap

Hashmap revision