Bump to 2.18.0.

Author: agraef

pd/src/m_pd.h

@@ -14,7 +14,7 @@ extern "C" {
 #define PD_MINOR_VERSION 48
 #define PD_BUGFIX_VERSION 0
 #define PD_TEST_VERSION ""
-#define PD_L2ORK_VERSION "2.17.0"
+#define PD_L2ORK_VERSION "2.18.0"
 #define PDL2ORK
 extern int pd_compatibilitylevel;   /* e.g., 43 for pd 0.43 compatibility */