Add out of bounds Ruby std::vector and std::array access testing

Also fix swig_assert_equal to work with nil as an expected input

Examples/test-suite/ruby/swig_assert.rb

@@ -22,6 +22,8 @@ end
 # msg   - optional additional message to print
 #
 def swig_assert_equal( a, b, scope = nil, msg = nil )
+  a = 'nil' if a == nil
+  b = 'nil' if b == nil
   begin
     check = "#{a} == #{b}"
     if scope.kind_of? Binding