heatmap cells drawn via document.createElementNS
begin detected datatype for drawing heatmap cells
null datatypes get a grey dot
nulls get grey rect and mutations get colored dot
methods to create svg elements for image, rect, circle
draw a ring in a cell
simplify css
methods to generate svg paths/shapes can now take a parameter to set any attributes instead of just the style attibute
separate assignment of style parameters
set ring color via data colorMapper
set up to allow multiple icons in the same cell - icons to be drawn in a single svg group element
set background for heatmap cells
make the cursor back into a pointer for the axes
library files for context menu
make axis text unselectable
test item in context menu
query string used to create query object
Got various icons to display in the cell.

Merge branch 'icon_in_cell'
instead of links, use the actual files