tell writer it has no outputs so as not to confuse paraview

also remove unused includes

Change-Id: Ia9282e411cc84b4b73a07c00ebe0512eb8a9cc2d
Fix time varying data writer looping.

Also had to correct a size conversion problem in ugrid topology.
That change probably makes it slower.

Change-Id: I9d1608b75fcaac436b4133393bc675153a9133b0
fix some warnings and improve some comments

Change-Id: Ic73560be0fe1e9c31d038b54da1b6e242f66e179
Fix remaining signed/unsigned comp warnings.

Change-Id: Ibb34702e8cc9824a299a854e4977ef74da811ab6