add initial jump instruction

lib/register/instructions/register_main.rb

@@ -0,0 +1,14 @@
+module Register
+
+  # This starts the register machine machine at the given function.
+  
+  # The implementation is most likely a jump/branch , but since we have the extra layer
+  # we make good use of it, ie give things descriptive names (what they do, not how)
+
+  class RegisterMain < Instruction
+    def initialize method
+      @method = method
+    end
+    attr_reader :method
+  end
+end