flatpak: set appdata release version for dev version: appdata file can now use a template (which has the same name with "_tpl_" prefix), which is used in dev version to automatically set the release with the right Mercurial revision/date. Comment from org.salutatoi.Cagou.appdata.xml has been moved as first child of <component>, so it is not lost while parsing the file.

These icons follow the Tango project [1] guidelines and have been downloaded from openclipart.org [2]

Free to use.

[1] http://tango-project.org
[2] https://openclipart.org