switch to meson build + refactor code to remove compile warning

diyac.c

@@ -24,9 +24,15 @@
 
 void help()
 {
+    printf("diyac - a simple Wayland compositor\n");
     printf("Usage: diyac [-x] [startup command]\n");
     printf("Options:\n");
     printf("  -x  exit with the session\n");
+    printf("  -v  increase log level\n");
+    printf("  -h  show this help message\n");
+#ifdef __COMPOSITOR_VERSION__
+    printf("Version: %s\n", __COMPOSITOR_VERSION__);
+#endif
 }
 
 /**