Adds tests for already implemented #is: very basic checks in the BaseImage,
which check if ColorForm is a color form, or a gray form, etc.
These already exist
Adds tests for the proposed changes of #is: at important locations.
Adds checks for #Collection, #Number, #Integer, #Fraction, #Character
and #String. So that the desired best practice usage of #is: instead
of #isString is enforced.
Adds tests for already implemented #is: very basic checks in the BaseImage, which check if ColorForm is a color form, or a gray form, etc. These already exist
Adds tests for the proposed changes of #is: at important locations. Adds checks for #Collection, #Number, #Integer, #Fraction, #Character and #String. So that the desired best practice usage of #is: instead of #isString is enforced.