anchor: Shader:sendColor
  Sends one or more colors to a special (''extern'' / ''uniform'') vec3 or vec4 variable inside the shader. The color components must be in the range of 1. The colors are gamma-corrected if global gamma-correction is enabled.
  
  Extern variables must be marked using the ''extern'' keyword, e.g.
  
  extern vec4 Color;
  
  The corresponding sendColor call would be
  
  shader:sendColor('Color', {r, g, b, a})
  
  Extern variables can be accessed in both the Vertex and Pixel stages of a shader, as long as the variable is declared in each.
  
  In versions prior to 11.0, color component values were within the range of 0 to 255 instead of 0 to 1.
  Shader:sendColor( name, color, ... )
  name string The name of the color extern variable to send to in the shader.
  color table A table with red, green, blue, and optional alpha color components in the range of 1 to send to the extern as a vector.
  ... table Additional colors to send in case the extern is an array. All colors need to be of the same size (e.g. only vec3's).