topic/snacman#130 blinnphong multilight

[Adnn]

closes #130.

• Add a suffix to the "entry" poser node-name.
• Show nodes with objects in pink in nodetree.
• Implement a multi-light BlinnPhong shading model.
• Transform ligts to be in camera space.
• Use UnitVec for directional lights' direction.
• First prototype of simulating reflection for Imgui automation.
• Use simulated reflection to complete the lights GUI.
• Fix the directional light: direction is now really the ray direction.
• Clear-up lights presentation, with separators and indents.
• Show point lights as debug cubes.
• Implement control over polygon mode in viewer forward pass.
• Handle bitangent in asset offline-processor and loader.
• Implement (first iteration) of normal mapping.
• Add an helper and commented out shader debug statements.
• Implement a solution to specular light bleeding (has drawbacks).
• Factorize Blinn-Phong lighting operation.
• Replace abrupt cut-off when facing away from light by smoothstep.
• Rename 'PhongLighting.vert' to 'FullVertexTransform.vert'.
• Add option to have directional lights in camera space.
• Implement a plain Phong shading model option.
• Offer macro control over TBN basis normalization.
• Make directional light white.