Added "V" and "T" aliases for "State.variables" and "State.temporary", accessible in any script, and replaced most of the usages

* 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.

- "New" is default renderer
- "Both" is always available
- "Debug renderer" is always available (enabled in options)
- "Colours" debug menu is always available, cheat mode enables character recolouring