Add support for depth and stencil texmaps

We should be able to attach these to colorbufs soon and do depth peeling,
shadow mapping, and more!

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Quaternion init from Euler angles

Signed-off-by: Paul Holden <paulholden2@gmail.com>
Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Unexpose object_get_fs_quad

This is kind of a goofy, hacky interface anyway, so let's kill it.

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>