Use '2'-bit of range field to flag hop-friend

Use '2'-bit of range field to flag hop-friend

The possibility to 'collide' from the hop platform by first stepping
back a number of squares before starting the second leg is now restricted
to one square, as indicated by the '1'-bit of the range field, for hoppers.
The '2' bit now flags that only a friendly piece can be used as platform;
an enemy counts as empty in the hop test, but because there is an actual
piece there it will terminate the ray (as no hop will reset that then).