Upgrade PDF output to 1-6

The current PDF output is version 1-4 this does not allow the creation of a PDF bigger than 200x200 inches that can be viewed in adobe reader (other viewers may not have this limit). If the output is upgrade to 1-6 then this restriction can be overcome. This would basically require scaling the request size to fit into the 200 inch limit internally then using /UserUnit in the writePage to scale this back to the required size.