Major reworking to support larger scale maps for some of the larger units. Buckingham for example would have taken almost a terabyte of memory to render. There are a few little niggly tweeks to fix but in the main this is a working version. However, on zoom there is not currently a change in map type to display the higher resolution image that is known about. However, the intrastructure is hopefully in place to make this fairly easy.
Merge pull request #4 from etothepii/feature/loadMapsAtDifferentScales

Major reworking to support larger scale maps for some of the larger Bounded Areas.