Automatic declaration of attribute, varying and uniform in ShaderityObjectCreator

[KaYaF]

It is useful if the attribute, varying, and uniform variables that you want to use in your function are automatically declared. If the user uses variables with the prefixes "a_", "v_", and "u_" in a function, it would be nice if they are interpreted as an attribute, varying, and uniform. The type and precision are automatically inferred if possible or let the user specify it in comments if it is difficult.