Cleanup comparisons

[eltoder]

• Fix comparing Money in Python: __eq__ and __ne__ were missing.

• Expose __cmp__ as compareTo() in Java. This is the correct name for this method. "compare" is for Comparators[1][2]. Note that this is only a change for Money. Period and Date did not have __cmp__ exposed in Java until #610.

• Remove __cmp__ and __nonzero__ methods from Python. These were Python 2 magic methods that are not used in Python 3[3].

[1] https://docs.oracle.com/javase/8/docs/api/java/lang/Comparable.html#compareTo-T- [2] https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html#compare-T-T- [3] https://docs.python.org/3/reference/datamodel.html

[eltoder]

@lballabio If you think it's worth it, we can put back Money.compare as a deprecated alias to compareTo using %proxycode and @Deprecated.

[lballabio]

Just compareTo is ok, I guess. Do these classes need to implement Comparable?

[eltoder]

Added Comparable<T> implementations.