Partial draft of PDF basemap (#12)
Uses jsPDF. Redundant dimensions. No download interface yet - just starts PDF download with `.save()`. Page not necessarily sized/oriented to fit image.
Map page size fit to image. Scale not yet correct (!= mapurl @ mapscale; fail)
scale correction
Draft ad panel (dummy AdSense add; no sponsor info link)
Replaced static img with AdSense code.
defer pdf download to link click after extrusion; super janky draft