Change Corner enum order to enable bit operations

[lucashilles]

Currently the Corner enum is ordered in such a way that it is not possible to differentiate the horizontal position using bit operations.

core/math/math_defs.h

enum Corner {
	CORNER_TOP_LEFT,
	CORNER_TOP_RIGHT,
	CORNER_BOTTOM_RIGHT,
	CORNER_BOTTOM_LEFT
};

Changing the order of the elements would make this kind of operation possible, as shown in the table.

T/B	L/R	enum
0	0	CORNER_TOP_LEFT
0	1	CORNER_TOP_RIGHT
1	0	CORNER_BOTTOM_LEFT
1	1	CORNER_BOTTOM_RIGHT

[AThousandShips]

This would break compatibility, so can't happen until 5.0 most likely

[Mickeon]

Sounds good, what's the necessity for it though?