Simple use of userpoints_userpointsapi overwrites parameter passed in.

After #441678: Use drupal_write_record(). Needed to be able to import transactions with migrate_extras, passing an integer into userpoints_userpointsapi causes the points to be overwritten, since they're being passed into the function by reference. I'm about to send a patch that resets the incoming $param variable to the original value if it isn't an array. Also suppling a test to ensure this doesn't happen again. This should also fix #560972: Wrong calculation of userpoints in case of points updates