#47 Bug - equals() methods overload instead of override Object.equals()

[Malcolm]

Some implementation of equals() methods are implemented as equals(SomeObjectType) instead of equals(Object). Thus they overload Object.equals(Object) instead of overriding it, and consequently strange behaviour is occurring.

Known cases:
* QueryableDatatype.equals(QueryableDatatype)
* DBOperator.equals(DBOperator)

I've committed nz.co.gregs.dbvolution.datatypes.DBIntegerTest showing a bug whereby DBInteger.equals() doesn't work correctly. The failing test case is @Ignore'd at the moment.

"@Override" annotation should be added to all equals() methods throughout DBv codebase to avoid this.

[Gregory Graham]

Well spotted and excellent write-up.

This is obviously not something I have done before but it's definitely a valid operation.

[Gregory Graham]

I've changed all the equals(*) methods to equals(Object)