Implement hashCode() and equals() for all the numeric types

[bdezonia]

This has not been done yet and thus creating hashes of these elements might be fundamentally broken. The equals() contract must decide to be strict (exact class type matches and element values match) or loose (a double could be equal to a byte or a short or an int or a long or a float or a double or all kinds of stuff).

[bdezonia]

Done on master