Fix toGeometry method in SpatialNetwork class.

Previous toGeometry method targets geometries of all levels.
New toGeometry method takes the argument of certain level and targets
geometries on it.
Remove 'connect' method and buffer parameters.

SpatialNetwork class should not support geometries which is not aligned.
Processing these geometries should be contained in other classes or
modules.
Rename the arrange method in TopoUtils to 'adjust'.

The word 'adjust' means that it changes the size of given geometries to
fit into given frame.
Add some detailed comments and remove one method in TopoUtils class.

The method toGeometry(env: Envelope) has the same function as
GeometryFactory's toGeometry method.
Add exAlign method for external geometry alignment.

This method is added with many sub-methods.
They have not been tested yet and need to be tested.