added support for multiple layers in snake and GoL

fixed dark mode font color

fixed font location

fixed text location and size and color

fixed update frames to current theme without needing to click around

Update README.md added new heatmap

added new example heatmap and heatmap animation

fixed delete frame

added example heatmap

Update README.md added heatmaps animations

added heatmaps

added undo and redo buttons

fixed a cell not being drawable

added randomize feature

adjusted block auto, spin tetrominos around