Added default implementation of #== to Hamster::Enumerable. SortedSet can now be compared with other sequential collections
Reorder methods in SortedSet
Updated style of SortedSet specs
Added a few test cases for SortedSet#at
Added a few test cases for SortedSet#find_index
Updated style of Queue specs
Stylistic tweaks to Vector.new specs
Added spec which tries randomly modifying Queue
EmptyStack must be frozen
Updated style of Stack specs
Added spec for Queue#dup
Stack prints 'top' item on the right

This more closely matches the expectations most Ruby programmers will have about
the behavior of a 'stack' object. Additionally, an inconsistency has been fixed,
where Hamster.stack(1,2) would return an object which prints as "Stack[1, 2]", but Hamster::Stack[1, 2] would return one which prints as "Stack[2, 1]".

The only downside is that Stack#each will be less efficient now. It must traverse
the list in reverse order, again to comply with what most Ruby programmers will
expect.
Added a new test for Hamster.stack
Added comment on Set#include? spec
Added a spec which does random pushes and pops on Stack