extracted interactive world styles into separate css file
new graphics assets for the interactive world
enabled foreground and background layers
removed all elevation info from the world's ground elements
removed actor from world (no longer exists in latest design concept)
demo world cleanup, with only two sectors and two levels
separated levels styles into distinct css files
moved level-specific graphics into a dedicated folder
updated usineio level styles to reflect new graphics files path and visuals
test styles for paris level
moved back world system global rules definition to webtales css
regrouped all z-index rules into a dedicated section to improve clarity
updated shelf left corner image that had an incorret y offset
(debug) filled paris level with some empty sectors for quick previewing