Move headers from server/include to include/maxscale

- Headers now to be included as <maxscale/xyz.h>
- First step, no cleanup of headers has been made. Only moving
  from one place to another + necessary modifications.

server/modules/include/avrorouter.h

@@ -20,16 +20,16 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <blr_constants.h>
-#include <gw.h>
-#include <dcb.h>
-#include <service.h>
-#include <spinlock.h>
-#include <mysql_binlog.h>
-#include <users.h>
-#include <dbusers.h>
+#include <maxscale/gw.h>
+#include <maxscale/dcb.h>
+#include <maxscale/service.h>
+#include <maxscale/spinlock.h>
+#include <maxscale/mysql_binlog.h>
+#include <maxscale/users.h>
+#include <maxscale/dbusers.h>
 #include <avro.h>
 #include <cdc.h>
-#include <maxscale_pcre2.h>
+#include <maxscale/maxscale_pcre2.h>
 #include <maxavro.h>
 #include <binlog_common.h>
 #include <sqlite3.h>