The `Solve' operation now rotates and/or reflects the solution grid

The `Solve' operation now rotates and/or reflects the solution grid
to bring it as close as possible to the current game state. This
means that if you request `Solve' after solving a puzzle yourself,
with the intention of finding out how similar your solution is to
the program's, then you will mostly see the differences in _shape_
rather than those being masked by the fact that yours happened to be
the other way up.

[originally from svn r6126]