Support handling of a 6k x 6k matrix/array

[Robert Leach]

No description provided.

[Robert Leach]

I created a 6k x 6k array for testing (by duplicating data until I reached the size). You can get it off the downloads page:

https://bitbucket.org/TreeView3Dev/treeview3/downloads/large_6kx6k.txt

[Robert Leach]

My test of 6k x 6k worked, but I think that we need to specify limits for individual dimensions. E.g., what about 200 x 180k? It's the same number of cells. So should that be supported? Perhaps we should test a 1 x 36M array.

[Robert Leach]

Lance pointed out that we can load larger than 6k x 6k. It's when the user goes to cluster when we should give a warning. See issue #62.

[Robert Leach]

This requirement is met, though a warning for larger data matrices should give a warning - see issue #62.