This simplifies both LOK API implementation and client code, and also
clients are no longer required to floor() the twip -> pixel conversion
result.

(cherry picked from commit 84dedf4f)

Conflicts:
	libreofficekit/qa/gtktiledviewer/gtktiledviewer.cxx

Change-Id: I63dbc05f53e8f7582b964c43d5da3aad51ede10d