[REVIEW-3-6] fix for fdo#52351, remove conditional formatting if all its cells are removed

[Markus Mohrhard]

Hey,

[1] is mostly a fix for a strange behavior of ScRangeList which
affects also conditional formats. ScRangeList did not delete a ScRange
if UpdateReference removed all the ScRange cells. The second step of
the patch is to remove the conditional formatting if the ScRangeList
is empty after updating the range.

Regards,
Markus

[1] http://cgit.freedesktop.org/libreoffice/core/commit/?id=76f56b5e8d4abf17682aa75b7cf183b883809234