Upload/Browse:  (1) Browse now supports searching for images with no value 1, no value 2, no date, etc.  (2) there used to be 3 things that could generate empty-string location values: upload with metadata from filenames, upload with metadata from CSV, and the browse metadata edit form. All 3 of these have been modified to save null location values instead of empty-string ones.  (3) rearranged the Browse code more, most notably to make patch mode work again.