Inconsitent use of HI inside GamepadPlugin

[DavidVollmers]

Hello,

HumanInput/src/gamepad.js

Line 241 in b96967b

this.HI.trigger(HI.scope + event, gp.buttons[j].value, gamepads[i]);

HumanInput/src/gamepad.js

Line 247 in b96967b

this.HI.trigger(HI.scope + event, gp.axes[j], gamepads[i]);

HI is used instead of this.HI which results in an error when managing the HI instance by yourself and when no global HI is defined...

A hacky hotfix for this issue can be:

eval( 'window.HI = { scope: "" }' )