Redesigned and cleaned up how the Grid_info class is initialised.
This is necessary as the grid_ops data structure was eliminated from the 1.3 line a long time ago.
Now the lower, upper, and inc data structure structures are passed in. In __init__(),
calc_grid_size(), calc_grid_values(), and calc_strides(), the code has been cleaned up, comments
added, and docstrings written.
