Change Mom to SlotMachine

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

lib/slot_machine/macro/set_internal_word.rb

@@ -0,0 +1,15 @@
+module Mom
+  class SetInternalWord < Macro
+    def to_risc(compiler)
+      compiler.builder(compiler.source).build do
+        object! << message[:receiver]
+        integer! << message[:arg1] # "index"
+        object_reg! << message[:arg2]#"value"
+        integer.reduce_int
+        object[integer] << object_reg
+        message[:return_value] << object_reg
+      end
+      return compiler
+    end
+  end
+end