Version 1.0.0

With this version, image-renderer exits alpha and becomes stable.

• Add some example scenefiles and scripts
• Add bash completions (#17).
• Improve the command line interface (#28).
• Implement a parser for scene files and a render action (#20, #30, #29, #32, #31).
• Implement PerlinNoise and some related textures (#24)
• Improve SpecularBRDF and implement DielectricBSDF (#24).
• Enable multithreading (#25).
• Bug fix: make Materials work with CSG shapes (#27, #26).
• Bug fix: make PathTracer work properly also without Russian roulette (#23, #21).
• Implement a DebugRender for better debugging (#22).