Merge pull request #415 from vandenoever/layouttests

Fix loading of webodf.css in qtjsruntimetest.
Make sure newly created ODT documents have valid manifest.xml and settings.xml files.
Add new layout tests.
Layout tests can be added in layouttests.xml. A file is constructed from
ODF fragments and the loaded and layed out document is checked.
Only a few simple dimensions for are currently checked, more tests will follow.