The getNextShape(pObj) method is just used for iterating over the complete
ShapeList. But the complexity for this operation is exponential.
When using getNextShape() iterating over the list have linear complexity.
In short: it is much faster.

Change-Id: I3896af2247f348153d62f2bcdd207c5a75239689
Reviewed-on: https://gerrit.libreoffice.org/4132Reviewed-by: Thorsten Behrens <tbehrens@suse.com>
Tested-by: Thorsten Behrens <tbehrens@suse.com>