move classes to support, allow dep injection to use other hash_map etc. e.g. mori

[shaunxcode]

It would be nice to move out the support classes for hash_map, vector etc. so that jsedn is mainly the reader and the underlying implementations can be changed easily. Technically this can be done already by just doing edn.Map = MyOtherMap so really this is just about breaking out the default implementations into their own file so that in theory one could build a version w/o them that would utilize mori or the es6 hashmap etc.

[typeetfunc]

@shaunxcode Thanks for great and very useful library. If you're interested i write babel plugin for precompile EDN into mori data structures. https://github.com/typeetfunc/babel-plugin-datascript#example