REORG: rename "pattern" files

They're now called "sample" everywhere to match their description.
diff --git a/include/types/acl.h b/include/types/acl.h
index 9e560cf..ed8582b 100644
--- a/include/types/acl.h
+++ b/include/types/acl.h
@@ -28,8 +28,8 @@
 
 #include <types/arg.h>
 #include <types/auth.h>
-#include <types/pattern.h>
 #include <types/proxy.h>
+#include <types/sample.h>
 #include <types/server.h>
 #include <types/session.h>