Moving the starting hex selection code.

Taking this out of the robot class and putting into the world class.
The world class will tell the robot where it needs to start from and we
will inject that into the robot initializer.

Also, need to remove the "selected" property of the hexagon and add in a
contains of different base object types so that we can have other types
of objects inhabit the world.
The bot doesn't have a current hex when it's created.

It gets a current hex when it is added to a world object.
Also need to move all the world scanning code out of the bot and into
the world.  The bot scans the world and the world returns a list of
adjacent sqaure.  The bot can then decide if it can move to them based
on height/distance.

We might need to allow the bot to decide an impossible move, say "Move
to NE to hex with height of 8" and the bot is at 4.  This move would not
be allowed and the world would return the result.
Broke something

Now the board won't draw.
The world draws correctly now.

I had a reference to an old List<Hexagon>.  Now we're working off the
hexworld.Tiles List<Hexagon>