Change Mom to SlotMachine

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

lib/slot_machine/macro/putstring.rb

@@ -0,0 +1,14 @@
+module Mom
+  class Putstring < Macro
+    def to_risc(compiler)
+      builder = compiler.builder(compiler.source)
+      builder.prepare_int_return # makes integer_tmp variable as return
+      builder.build do
+        word! << message[:receiver]
+        integer! << word[Parfait::Word.get_length_index]
+      end
+      Mom::Macro.emit_syscall( builder , :putstring )
+      compiler
+    end
+  end
+end