Bugfix #5030

- Removed obsolete IRIZ image support from menus.
  This was a Blender-only version of SGI Iris images, used internally in
  the nineties because it was the only format supporting Z easily
  A much better Z exporting - and industry compliant - is via OpenEXR

- Scene strips in Sequencer now get Z buffers as well. This is only in
  float format, containing actual distances from the camera.

source/blender/src/sequence.c

@@ -931,7 +931,8 @@ static void do_build_seq_ibuf(Sequence * seq, int cfra)
 					se->ibuf= IMB_allocImBuf(rres.rectx, rres.recty, 32, IB_rectfloat, 0);
 					memcpy(se->ibuf->rect_float, rres.rectf, 4*sizeof(float)*rres.rectx*rres.recty);
 					if(rres.rectz) {
-						/* not yet */
+						addzbuffloatImBuf(se->ibuf);
+						memcpy(se->ibuf->zbuf_float, rres.rectz, sizeof(float)*rres.rectx*rres.recty);
 					}
 				}