Update to 1.19
    
    - New upstream release 1.19
      - Add pod link to YAML::Shell (GH#164)
      - Fix infinite loop for aliases without a name (GH#151)
      - Improve error messages (GH#142, GH#162)
      - Trailing spaces after inline seq/map work now (GH#163)
      - Add test case for trailing comments (GH#154)