Issue with multiple joysticks

[Xamyrz]

Describe the bug the "touchend" event should be listening to "canvas" rather than "document", as in my webapp, when i want to have 2 joysticks, and I let go of one of them, the "touchend" event gets fired on both of the joysticks.

To Reproduce Steps to reproduce the behavior:

1. add 2 joysticks
2. touch 2 at the same time
3. let go of one
4. "touchend" will be fired for both joysticks, rather than just the one.

Expected behavior touchend fired on the joystick that actually initialised it, rather than both

Screenshots

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6] ALL DEVICES
• OS: [e.g. iOS8.1] ALL OS's
• Browser [e.g. stock browser, safari] ALL BROWSERS
• Version [e.g. 22] ALL

Additional context None