update function
add an event to the update function
| Parameter | Type | Description |
|---|---|---|
| canvas | String | name of canvas to add event to update function |
| name | String | unique name of the update event |
| event | Function | event to add to update function |
remove an event from the update function
| Parameter | Type | Description |
|---|---|---|
| canvas | String | name of canvas to remove event from update function |
| name | String | name of the update event |