Add output functions for Atom
Minor documentation fixes
Document Atom.to_xml and Atom.output
Use "link list" consistently for "links"

Closes https://github.com/Cumulus/Syndic/issues/37
Merge new error and tree definitions
Adapt the XML generation to the new tree definition
Add Atom.aggregate
Update to the new <id> representation
Use OASIS dynamic mode for development

A rule to create a tarball independent of oasis is available.
Fixes https://github.com/Cumulus/Syndic/issues/34
Merge the conversion function RSS2 → Atom
Add Syndic_conf to the modules of the library
Remove horizontal lines in "section" comments
Merge pull request #33 from Chris00/master

Add output functions + feed aggregation for Atom