API changes/cleanup.

API changes/cleanup.

API changes:
    - include/canvas.js renamed to include/display.js
    - Display.rescale() method removed from API. Use Display.set_scale() instead.
    - Make logo configuration attribute of Display and display it when
      clear() is called if it is set.

API deprecations:
    - use RFB onUpdateState instead of updateState.
    - use RFB onClipboard instead of clipboardReceive.

See https://github.com/kanaka/noVNC/wiki/ModuleAPI for detailed noVNC
modules and API description.

Expand and normalize the event/callback interfaces. Standize on
"onEventName" form for callbacks.

    Callback Renames:
        - RFB updateState -> onUpdateState
        - RFB clipboardReceive -> onClipboard
        - Keyboard keyPress -> onKeyPress
        - Mouse mouseButton -> onMouseButton
        - Mouse mouseMove -> onMouseMove

    Callback Additions:
        - RFB onPasswordRequired
        - RFB onBell
        - RFB onFBUReceive
        - RFB onFBUComplete

Other:
- Add array type support to Util.conf_default()
- Removed a bunch of routines from the Display API that were just used
  internally and not actually by noVNC: flush, setFillColor,
  imageDataGet, imageDataCreate, rgbxImageData, rgbxImageFill,
  cmapImageData, cmapImageFill.
- More keyboard/mouse logging when debug turned on.
- Some JSLinting