[develop] Performance Improvements (Markers, MarkerClusterer Rewrite)

Performance tweaks via @ccg1415 and [Realmassive.com](https://www.realmassive.com/search/Austin+TX/Office)

You can see how much faster things are there for yourself.

- lazyUpdate map.coffee
- modelsByRef to disable equality checks
- marker managers improvements (MarkerClustererPlus dropped from google tools sdk)

This is to open up this major PR for discussion how to handle merging in these changes.


Do you have specs for this? With benchmarks?