Default filename for SQLite file will be dev_XYZ where XYZ is the dev…

…ice ID. User can also provide a filename, but using this default will prevent troubles when the device name is too long, contains weird characters, etc... This should solve issue #245

BAC0/sql/sql.py

@@ -155,7 +155,7 @@ def save(self, filename=None, resampling=None):
                 filename = filename.split(".")[0]
             self.properties.db_name = filename
         else:
-            self.properties.db_name = "{}".format(self.properties.name)
+            self.properties.db_name = "dev_{}".format(self.properties.device_id)
 
         if resampling is None:
             resampling = self.properties.save_resampling