Added SGUI_CUSTOM backend type

SGUI_CUSTOM simply creates a window with no canvas. A user can use the
*_get_internal functions to retrieve internal data structures and
operate on them.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Exposed Direct3D 9 context struct

 - removed reset call, must be done manually be user as
   reset requires reload of all resources
 - fixed present parameters for devicess with no depth buffer

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Added (not really rotating) foreground triangle to d3d9_1 sample

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>
Added Direct3D 9 device lost event

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>