grfcodec: 6.0.4-1~getdeb1

  * New upstream version
    - NFORenum specific changes:
      - Data file updates
        - Action 0, feature 0xF, property 0x18 (Object amount on map)
        - Action 2 train and road vehicle variable 4D
        - Action 2 object variable 60
        - Action 5, type 0x15 (OpenTTD GUI): Now 175 sprites are allowed
      - Support string codes 9A 16 to 9A 1D
      - Allow higher IDs for vehicles when GRF version >= 8
      - Fix some checks for sprite numbers >= 65536
    - Remove grfdiff and grfmerge due to being unmaintained