Remove monkeypatch of Array#==

[neilconway]

Right now, we monkeypatch Array#== so that array literals and Bud tuples can be compared for equality. Monkeypatching such a fundamental method is a bit unfortunate (as the comment in monkeypatch.rb notes); it also has a performance cost. If the only thing this is useful for is the test cases, that should be easy to fix (e.g., add an assert_tuple_equal method to MiniTest). On the other hand, we've claimed in various places that Bud tuples are arrays, so not allowing tuples and arrays to be compared for equality might be unexpected.

[neilconway]

Note that if we do keep the current Array monkeypatch, the current implementation needs improvement:

1.9.3-p125 :001 > class Array
1.9.3-p125 :002?>     alias :oldeq :==
1.9.3-p125 :003 >       def ==(o)
1.9.3-p125 :004?>         if o.kind_of? Struct
1.9.3-p125 :005?>             o = (o.to_a)
1.9.3-p125 :006?>           end
1.9.3-p125 :007?>         self.oldeq(o)
1.9.3-p125 :008?>       end
1.9.3-p125 :009?>   end
 => nil 
1.9.3-p125 :010 > 
1.9.3-p125 :011 >   C = Struct.new(:x, :y)
 => C 
1.9.3-p125 :012 > j = C.new(1,2)
 => #<struct C x=1, y=2> 
1.9.3-p125 :013 > j == [1,2]
 => false 
1.9.3-p125 :014 > [1,2] == j
 => true 

[neilconway]

On reflection, I think this is fine. The issue raised in the comment is bogus (we override Struct equality so that behavior isn't accurate), and continuing to support the ability to compare Bud tuples and arrays for equality seems useful.