Added a new type: MultiArray which can iterate over multiple arrays.

Example:
	[1,3]:[2,4] each {|a,b|
	   say "#{a} #{b}";      # prints: 1 2
				 #         3 4
	};

	MultiArr.new(["a","d"], ["b","e"], ["c","f"]).each { |a,b,c|
	   say "#{a+b+c}";    	# prints:  "abc"
				           "def"
	}

Added <enum>eration support;

Example:
	enum |White, Black|;
	say White;	# prints: 0
	say Black;	# prints: 1

	enum first;
	say first;	# prints: 0