Draft: Fix/reference overwrite

Branch to fix the problem of objects overwriting the enum dictionaries of previously-created objects.

The problem was that properties is a class attribute on text_array (or any other GeneralContainer but text_array is the example in the test cases), so when facility inherits from text_array, it also gets properties as a class attribute that points to text_array.properties. I understood class variables well enough, but didn't realize that they have the same exact behavior for objects of the same class as for objects of an inherited class.

The child class' class attribute can be set to not point to the parent attribute by giving it a value in the definition of the child class. The Container class factory (container.py) sets the property attribute to an empty dictionary, then fills in the dictionary with the values from text_array.properties (since the schema files only require the information that is different from the GeneralContainer). Then it loops through the input schema to change/add any values that were given in the schema. This all starts in container.py on line 49.

Other changes:

• before this, the property attribute was updated after the Container was created, right before the class factory returns the Container class. These lines were removed.
• formatting
• deleting unneeded variables after using (because with class factories, these "temporary" variables actually end up being class attributes
• cleaned up some imports