Add Rotate property to PDFPage
Update DocumentContext::WritePage() to write the '/Rotate' key
Check inRotate argument of PDFPage::SetRotate() to be a multiple of 90
Add PDFPageInput::GetRotate() method
Add RotatedPagesPDF test to make sure the page rotation works
Extend the RotatedPagesPDF test to check parsing as well as writing
Add test for invalid rotation (must be multiple of 90)
Change test to create 6 pages (in order to test rotations beyond 270 degrees)
Merge pull request #21 from filodej/filodej/pdf-page-rotation

PDF page rotation