Updated current usage for ColorCorrection to reflect ColorCollection existence.
Adds _remove_xlmns private func which removes the xlmns namespace attribute from any incoming XML file, returns the XML element
Changes returns for child lists of ColorCollection to be tuples. Adds methods for appending.
Reordered ColorCollection to be below ColorCorrection and ColorDecision so that it could reference those classes.
Updated test to reflect that ColorCollection.color_corrections now returns tuples not lists.
Adds append_child and append_children to ColorCollection's docstring
Adding usage documentation for current (and planned) features of ColorCollection