Processed properties should be able to be compared to one another

[Sam Brockie]

Example would be:

from pyproprop import processed_property

class SomeClass:

    some_property_min = processed_property(
        "some_property_min",
        description="some property's minimum bounded value",
        less_than="some_property_max",
    )
    some_property_max = processed_property(
        "some_property_max",
        description="some property's maximum bounded value",
        less_than="some_property_min",
    )

Uses new keyword:

• less_than
• greater_than
• at_least
• at_most
• equals