Add basic pdf support based on pdfjs. If you check in a new version of pdfjs,
please use the google closure compiler with following command, to compress the
really huge library.

$ java -jar compiler.jar --js ./build/pdf.js --js_output_file pdf.js
--language_in=ECMASCRIPT
Grid visualizer will also react to page number events.
PDFViewer class must hold the input, wrapper and visToggle state.
use the result id of the vis input for pdf html id
forgotten to set the id
add pdf icon to grid view
when clicking the pdf visulizer button load manual load the first page
Get page number annotation which dominates an event.
Set toggle button for visualizer to collapse, when expanding preloaded
visualizer.
Get error message when initializing of grid vis fails.
Changing the grid visualization works pretty good, but it seems there is a race
condition between visualizer panel and pdf viewer, when setting the visualiztion
visibility to true.
Avoid the cycle with calling of openPDF.
ake the pdf_support working again after rebasing the master