This release contains several backwards compatibility breaks that will effect
more advanced usage of Parity, however the common usage via Parity::compare()
is unchanged.

• [BC] Drop support for PHP 7.1
• [BC] Add parameter and return type hints
• [BC] Remove PackageInfo class
• [BC] Rename ComparatorInterface to Comparator
• [BC] Rename AnyComparableInterface to AnyComparable
• [BC] Rename ExtendedComparableInterface to ExtendedComparable
• [BC] Rename SelfComparableInterface to SelfComparable
• [BC] Rename SubClassComparableInterface to SubClassComparable
• [BC] Remove AbstractExtendedComparable class, use ExtendedComparableTrait instead