* Fixed error that could happen on layers with certain processing setups (like masking without recoloring)
* Unified system for layer processing steps
* Renderer performance is logged to Perflog

Fixed monster hoodie sleeve accessories not showing by adding clothing setup property sleeve_acc_img:1

* Expanded short form of gradient spec - any stop can be just a color; the offset would be auto-generated.
* Added ability to animate some layer properties
* Improved canvas animation performance a little (frame is skipped if previous is not done yet)

* Error reporting button not hidden during intro

* Added support of mask images in the renderer (layer property `masksrc`). Mask images determine which parts of the layer will be shown and which removed.
* Head clothing can have mask.png image that will be applied as such mask to hair and ears. Indicated by setup property mask_img:1.
* Added mask image to hoodie hood.

  - small button in sidebar to display errors
  - copy all errors at once
  - limit of 100 errors
* Renderer errors that happen in callbacks not captured by SugarCube are logged
* 'Refresh caches' button in renderer debugger
* Split canvasmodel-utils.js from canvasmodel.js, making latter handle only CanvasModel code

* safeguarded against upper accessories going below breasts

* Renderer image loader can be customized (not used yet)