Refactor VolumeMap needed

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VolumeMap works. But it's time for a refactor. Here is a quick 5 min run-down 
of what needs to be change.

1.)
VolumeMap internally should use page x,y. Try to eliminate the page ID to long 
pageX, Y conversion as much as possible. 

2.)
PageRegion should be refactored so it stores the computed value such as page x, 
y. Currently, there is a lot of conversion going, conversions that can be saved 
and reused across different methods. 

3.)
We need to move all the addressable to be vector3s instead of all vector2 as we 
are doing now. Even if we are completely 2d at the moment. 

Original issue reported on code.google.com by LLw...@gmail.com on 11 Feb 2011 at 11:54

[GoogleCodeExporter]

4.) 
We need to consolidate a few methods to use the same helper methods. Well, it's 
not too bad. There is one method where we implemented some helper method after 
that method, so we need to update it to use the helper methods.

Original comment by LLw...@gmail.com on 11 Feb 2011 at 11:56