bnc#657899: Paragraph vertical spacing differs from PowerPoint

We need to set the "paragraph summation" flag also for .pptx import. (As is
already done for .ppt import.)

This is what in the Options (Preferences) UI is called "Add spacing between
paragraphs and tables (in current document)", on the LibreOffice
Impress:General page. This is a setting that when set becomes local to the
document. I actually don't really understand why this needs to be a
user-visible option, wouldn't it be enough for it to be an internal flag that
is set for documents imported from .ppt and .pptx, and is clear otherwise?

Change-Id: I525178957276e7d587b6ac4be8ae7919fc245a27
Bin commented-out #defines

Change-Id: I01f473658708a75c3eac6219efd38cd8ec5aa44f
Bin EE_CNTRL_URLSFXEXECUTE which was only set, never tested

Change-Id: I18a9355bb902b19f0eeecb26d33eba4fb25db8cb