improved connectivity webGL viewers

added lighting; fixed context menu position; improved ear and nose rendering;
made canvas fill parent container on width;
fixed zooming -- now is persistent on tab change
fixed some typos and JSDocs
added legend for local connectivity

refactored code such that local connectivity uses its own drawScene
removed some unused variables and fixed some JSDocs
added branding bar on exported png images
added branding bar on exported SVG images
gave relevant names to exported figures
TVB-974 fixed MPLH5 canvas resizing on export