Add handleMouseMove to CellEvents
Change cell events tests to use an array of toggled cells
Handle moving the mouse between cells and toggling them in the right scenarios
Finish handling mouse events for cells by handling mouse up
Hook up the cell toggling from CellEvents to the game of life app
Get the game to draw the cells that get added by the mouse
Fix bug where removed cells were still drawing.  Next step is to figure out why everything is so slow
Improve performance by drawing the grid as a single path instead of multiple paths