OK... recentering and zooming at initial start up works now.  A calculation
error where a Math.min was used instead of Math.max.  For every initial layout
of the graph, the MotherShip will find an appropriate zoom to fit all verticies
in there at the start.  The layout may still occlude some nodes (as larger nodes
may be overlaied on top of a smaller one).

- implemented a better circle layout that takes in the sizes of the vertices
into account.  This alleviates the layout problem somewhat, but not a perfect
fix, as large vertices may still eclipse small ones.

- implemented mechanisms for auto zoom/ center at start.  Does not work
perfectly, but combined with the better layout above, much less user interaction
is required to start browsing.

Also, would be nice if when starting up the mothership:
- the option "Draw content of the nodes" is selected, 
- the main circle is centered in the middle of the screen (instead of user
needing to double click on it each time at startup)