minimal refactor of the width/height calculus logic used by both layout() and setupPDF(): it is now contained in getViewportAndSlideDimensionsInfo() and includes a few improvements:
minimal refactor of the width/height calculus logic used by both layout() and setupPDF(): it is now contained in getViewportAndSlideDimensionsInfo() and includes a few improvements:

- the calculated available area numbers are rounded own to whole pixels

- setupPDF() did not recon with the fact that config.width and config.height MAY be specified as 'percentages of available space'; now it does.

- both PDF and display now use the config.margin factor.

GerHobbelt/reveal.js,GerHobbelt/reveal.js,GerHobbelt/reveal.js