Reflection, WeakHashSet, EmptyPair, and More

This is the largest release of JavaUtilities so far, bringing helper classes for dealing with Reflection, a copy of HashSet that uses a WeakHashMap for the backing map, an EmptyPair and more.

Changes

• Added classes for dealing with Reflection.
• Added a WeakHashSet which is a HashSet that uses a WeakHashMap for the backing map.
• Added an EmptyPair. Much like an empty optional there is only one instance of this.
• Added a ThrowableSupplier, a copy of the Supplier class but in which the #get() method throws a generic exception.
• Added a Primitive Enum for converting between primitive classes and their wrappers.
• Other various miscellaneous changes.