sim/field

This package holds common representations of space in MASON simulation models.
This includes 2D and 3D continuous space, 2D and 3D grids of various kinds,
2D hexagonal grids, and networks.  Such representations of space are called,
in MASON parlance, 'fields'.

The subpackages are:

grid		2D and 3D grids (square, hexagonal, toroidal, etc.)
continuous	2D and 3D continuous space
network		Networks (graphs)


Classes:


SparseField.java

An abstract superclass of certain fields in which objects are simply associated
with locations rather than stored in an array etc.  SparseField does this with
a hash table.
