Update dicom tables when database directory changes

Fixes #427
Merge branch '427-table-update'

* 427-table-update:
  Update dicom tables when database directory changes
Fix mark_as_superbuild when used with cache variable containng a colon

Also added the corresponding test.

Thanks @pieper for reporting the issue and testing.

See #418
Merge branch '418-support-use-system-option'

* 418-support-use-system-option:
  Fix mark_as_superbuild when used with cache variable containng a colon