Correct coordinate calculation for rectangle

[vanicat]

The new computation

• scale the rectangle as anyother coordinate
• use self.tiled_map.map_size.height * self.tiled_map.tile_size[1] to offset the y coordinate, otherwise they are negative.

Fix #1740

[pvcraven]

Looks like it didn't pass tests? Please research if you could.

[gran4]

Re-Add the 2 lines(921 and 922):
x = cur_object.coordinates.x + offset[0]
and
y = cur_object.coordinates.y + offset[1]
You deleted. Without them, x and y don't exist.

[vanicat]

I will look at the test after the end of Ludumdare,

[vanicat]

I've updated the patch, and it now pass all the test.
The two line proposed by gran4 was not correct, because the offset must be apply after the scaling (at least, it is what happen for others coordinate computation).

Thanks.