Allow different matcher with no GPS

opendm/osfm.py

@@ -214,8 +214,8 @@ class OSFMContext:
                 "bruteforce": "BRUTEFORCE"
             }
 
-            if not has_gps:
-                log.ODM_INFO("No GPS information, using BOW matching")
+            if not has_gps and not 'matcher_type_is_set' in args:
+                log.ODM_INFO("No GPS information, using BOW matching by default (you can override this by setting --matcher-type explicitely)")
                 matcher_type = "bow"
 
             if matcher_type == "bow":