================================================================
Structure
================================================================

packages:

util.......................generic utilities
math.......................mathematical types, functions, and constants
surface....................surface subsystem
geom.......................geometric objects (includes front-end to surface/)
message....................message-passing subsystem
kernel.....................network model built from message/
ui/base....................platform-independent GUI (implementation is hidden)
ui/extra...................extra GUI objects
base.......................generic utilities for a graphics engine
types......................concrete base types (real, complex, etc)
engine/dimn................n-dimensional engine (base classes for 3D and 4D)
engine/dim3................three-dimensional engine
engine/dim4................four-dimensional engine
components/dimn............components built from engine/dimn
components/dim3............components built from engine/dim3
components/dim4............components built from engine/dim4
viewers/dimn...............base classes for viewers/dim3 and viewers/dim4
viewers/dim3...............3D viewers built from components/dim3
viewers/dim4...............4D viewers built from components/dim4


dependency graph:

        util
         |\ \
         | \ \
         |  \ +----------------------------+
         |   \                              \
         |    +-----------+    math          \
         |                 \    |\            \
         |                  \   | \            \
         |                   \  |  +----------+ \
         |                    \ |              \ \
         |                     \|               \ \
      message                  base            surface
         |                      |                 |
         |                      |                 |
         |                      |                 |
         |                      |                 |
      kernel                  types               |
         |                      |\                |   
         |                      | \               |  
         |                      |  +----------+   |
         |                      |              \  |
      ui/base                   |               \ |
         |\                     |               geom
         | \                    |
         |  +-------------+     |
         |                 \    |
         |                  \   |
         |                 engine/dimn         
         |                      | |  \         
         |                      | |   \
         |                      |  \   +------------+
         |                      |   \                \                
         |                      |    \                \                
         |                      |     \                \                 
         |                      |    engine/dim3      engine/dim4
      ui/extra                  |         |               |
          \                     |         |               |
           \                    |         |               |
            +-------------+     |         |               |
                           \    |         |               |
                            \   |         |               |
                        components/dimn   |               |
                               / |  \     |               |
                              /  |   \    |               |
                             /    \   +-- | --------+     |
                            /      \      |          \    |
                           /        \     |           \   |
                          /          \    |            \  |
                         /            \   |             \ |
                        /         components/dim3    components/dim4
                        |               /               /
                        |              /               /
                        |             /               /
                  viewers/dimn       /               /
                        |           /               /
                        |          /               /
                        |    +----+               /
                        |   /                    /
                        |  /                    /
                  viewers/dim3                 /
                        |                     /
                        |                    /
                        |    +--------------+
                        |   / 
                        |  /  
                  viewers/dim4