[d3] create game function to initialize the game

Also remove unnecessary global variables.
[d3] Use d3 for styling and iteration
[d3] refactor to reusable charts idiom
[d3] Remove data-card-id attrib in favor of .datum()
[d3] remove data-section-id in favor of .datum()
set draggable=false on img tags
big mess of a commit

no idea if it works in this state