Disable debug menu and other shortcut keys before release

[mjslee]

Just a reminder that this should happen before both the pilot and the full study are released.

[mjslee]

Resolved. Added multi-key press detection as suggested by Andy.

• ALT was not a reliable combination key because on a mac, it activates an alternate character set.
• CTRL was not a reliable combination key because it gets interpreted differently across platforms and browsers
• SHIFT was the only reliable option across browsers. However, it is quite common to use it with keystrokes. So, I made a toggle button.

These are the keys:

1. shift + ~ == Toggle other options
2. shift + _ == Toggle debug pane
3. shift + { == Play intro
4. shift + } == Toggle avatar selection pane
5. shift + | == Toggle post survey
6. shift + + == Goto next level

To access the debug options, you must first press "shift + ~" to enable all the other options. In the case of toggled panes, you must press "shift + ~" to close the pane.