Removed Model from grid class names.
Added RasterGrid class for uniform x and y spacing.
Added __init__.py to unstructured subpackage.
Added links module for working with link on unstructured grids.
Added status module for adding node status to a grid.
Defines base class for unstructured grids.
Unit tests for link functions.
Added LinkGrid class.
Added JaggedArray class.
Changed to store values as numpy array.
Added cells.py that defines CellGrid.
Added alternate constructor that takes an array of arrays.
Added getters for array and offset arrays.
Changed to use JaggedArray class.
Updated tests for functions that return link counts not offsets.
Added nodes.py module for NodeGrid class.
Added n-D support for NodeGrid.
Changed to embed NodeGrid, CellGrid, LinkGrid.
Added some LinkGrid and CellGrid methods.
Added documentation and doctests.