Make Beamer able to generate asymetric two-screen presentations

Originally reported by: Vedran Miletić (Bitbucket: rivanvx, GitHub: Unknown)

From Stanislaw Polak:

"I use the \setbeameroption{show notes on second screen=left} option to divide a slide into two equal size parts / rectangles (left part with notes and right part with a content). I use the "Impress!ve" application, under Linux, to display my presentation. Because my laptop has possibility to use an extended desktop, Impress!ve displays the left part (the notes) on my laptop's screen and the right part (the content) on a projector. Presentation is displayed properly if both the laptop and the projector use the same resolution. If they use two different resolutions, a fragment of other part is visible, i.e., students see the whole content of a slide and a fragment of the part with notes. I have a proposition - a new option should be added to the Beamer class. Thanks to this option, a user could set that the left part will be displayed in 1680x1050 while the right part in 1024x768, and the Beamer class should divide the slide into two proportional parts (different size of rectangles (parts), different size of fonts, ...)"

• Bitbucket: https://bitbucket.org/rivanvx/beamer/issue/40