v1.4.0

• Changed: ToneMode, ColorMode, BlurMode can be changed only in editor.
• Changed: Cutoff's level is reversed.
• Feature: Exclude unused shader variant from build.
• Add: Add many materials for shader variant, but exclude unused materials from build.
  Build report of demo project is as following.

	ver.1.3.0	ver.1.4.0
UI-Effect.shader	All 112 variants, 170.7 kb	21 variants, 31.4 kb
UI-EffectCapturedImage.shader	All 80 variants, 49.0 kb	2 variants, 7.3 kb
Materials in build	Instantiate on play, 0 kb	23 items, about 5.0 kb
Total	219.7 kb	43.7 kb