wumpus

Copperbox revision 2314.

I've changed the LengthTolerance class to Tolerance and added a member for equality - equality is expected to need more accuracy than length.

Note - the Tolerance class is probably better in Wumpus-Core than Wumpus-Basic, then Eq on Points and Vectors could be tolerant. However there might be cases where this behaviour is not wanted and I need to think about the consequences of doing this a bit more...