v0.11.0

Transparency: give voxels a blend mode and opacity, so models, clips, and
procedural effects can be glass, glowing energy, or soft smoke instead of solid.
Requires roxlap 0.17 (per-voxel clip materials + the volumetric blend mode).

Added

• Per-colour materials. Each colour used in a model gets a blend mode and an
  opacity in the tool panel's new "Materials" section, composited live in the
  preview:

  • Alpha — front-to-back glass / water.
  • Additive — order-independent glow, for spells / fire / energy.
  • Volumetric — depth-weighted opacity, for soft smoke / fog.

  Opaque is the default, so an all-opaque model renders exactly as before.
  Material edits are undoable (a slider drag is one step) and saved in the
  .demiurg project.

• Clip transparency. A clip carries one material table shared by every
  frame; converting a translucent model to a clip keeps its materials. While a
  clip is playing, the preview runs through the engine's real clip player so
  the transparency matches what the game shows.

• Translucent procedural presets. The Rhai generator gains a
  material(col, mode, alpha) call so a script can declare its own materials —
  the Smoke preset is now volumetric fog and the Energy preset an
  additive-glow sphere.

Notes

• Materials are kept in the lossless .demiurg project only; the .kv6 and
  .rvc exports have no material channel yet, so they load back as opaque (the
  same boundary as enclosed interior voxels). Projects saved before this release
  load unchanged (all-opaque).