Log Message:
Update to 0.19

Upstream changes:
0.19  2018.10.20 MANWAR
      Fixed SEE ALSO broken links
      Tidied up Changes file
      Updated link to GitHub repo.
      Add --span flag
      Add --id flag to include ids in the html files. Default to noid.
      Add --force flag to the command line script to overwrite exisiting file.
      Default of script/trac2html is to exclude class=""