Change Mom to SlotMachine

rather large commit, but essentially a simple rename
Rationale in docs and blogs

lib/slot_machine/macro/div4.rb

@@ -0,0 +1,17 @@
+module Mom
+  class Div4 < Macro
+    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