update of d3-selectable to work with v4 of d3.js also added functionality for using cmd on mac.
Original repo: https://gist.github.com/jo/4068610 By: Johannes J. Schmidt, TF
Provide selection capabilities for DOM elements, geared to <select multiple>.
click: select elementctrl + click: add element to current selectionclick + move: select elements while draggingctrl + a: select all elements within focused listctrl + shift + a: deselect all elements within focused listctrl + click + move: toggle selection while draggingshift + click: select range from nearest last selected element to clicked elementshift + ctrl + click: add range to current selectionshift + clickbetween selected elements: select all between first and last selected elementhome: select first elementctrl + home: add first element to selectionend: select last elementctrl + end: add last element to selectionup: select element before first selected elementctrl + up: add element before first selected element to selectiondown: select element after last selected elementctrl + down: add element after last selected element to selection