Fix relative move commands following a path close.

Fix relative move commands following a path close.

Both 'M' and 'm' are moves and therefore start a new (sub)path. In
either case the location should be cached so that a later 'close path'
(z or Z) knows the location it is returning to. The location is not
written to 'p', since it is assumed that the client code remembers. If
the next move is relative (lowercase), then it's important that last_x,
last_y were correctly updated while processing Z/z.