Extracting the mom instruction from builtin modules

Since they were embedded at first (easier copy/paste) they now got own files, like their brethren
also mini tests for each instruction , nice start

lib/mom/builtin/div4.rb

@@ -0,0 +1,19 @@
+module Mom
+  module Builtin
+    class Div4 < ::Mom::Instruction
+      def to_risc(compiler)
+        builder = compiler.builder(compiler.source)
+        integer_tmp = builder.allocate_int
+        builder.build do
+          integer_self! << message[:receiver]
+          integer_self.reduce_int
+          integer_1! << 2
+          integer_self.op :>> , integer_1
+          integer_tmp[Parfait::Integer.integer_index] << integer_self
+          message[:return_value] << integer_tmp
+        end
+        return compiler
+      end
+    end
+  end
+end