resolves #303 use map for ViewerPreferences; set initial magnification
resolves #303 use map for ViewerPreferences; set initial magnification

- use map for ViewerPreferences
- enable /DisplayDocTitle preference to show doctitle in window title bar
- use /OpenAction to set initial magnification
- don't use /FitWindow (it changes the window size to fit the document)

mojavelinux/asciidoctor-pdf,dsisnero/asciidoctor-pdf,Hextremist/asciidoctor-pdf,asciidoctor/asciidoctor-pdf,dsisnero/asciidoctor-pdf,mojavelinux/asciidoctor-pdf,asciidoctor/asciidoctor-pdf,Hextremist/asciidoctor-pdf