Change single voice PDF page to A4 landscape

Added new parameters ```PrintParam.DEFAULT_A4PartLandscape``` so the voices are rendered in the PDF on A4 landscape pages.

Using the ```PrintParam``` is also a better way to solve the problem addressed in pull request #7.
cool, i like the look of this A4 landscape layout. the old "page-size-fits-music" parts layout was only used for print-ready book examples, so i'm happy to replace it.