Changed depth sorting algorithm.

Changed depth sorting algorithm.

Opaque items are sorted first by depth index, then by Shader, Geometry and Material.
Transparent items are sorted first by depth index, then by distance from camera, then by
Shader, Geometry and Material.

Changed the render algorithm to interleave the opaque and transparent lists for
items at the same depth index.

Change-Id: I2c21c986d790a4ac0f2a519e1bb58242537f4f8a
Signed-off-by: David Steele <david.steele@partner.samsung.com>