export smooth property correctly to OOXML, fdo#74619

MSO 2007 and later have different behavior for the default value.
Be explicit and always export the element.

Change-Id: Ic8cad67db8c882d3642a6662bf710be2088335b7
adapt smooth import to OOXML and not to MSO 2007

Change-Id: Id1dc62a89e2858f81dc9b6eb8a5f3d9996ba85ec
enable smoothed property export for line charts, fdo#74619

Change-Id: I1b9796411a6f688f2bc7c53212fb4245c55ab3e1
add test for fdo#74619

Change-Id: I94ed07b730b976f32ce8572f1ccefa96be0a6e77
set first position and then size, fdo#75075

Change-Id: Ica8a82619f492bd30929ce88198f621f7a1f88a2