Replace Genshi by Kajiki in Relatorio

Description:

Tryton uses Relatorio has template engine. It uses Genshi as internal engine but Genshi is no more so well maintained. So the idea is to migrate to Kajiki which has a very closed syntax and so limit the incompatible changes.

https://groups.google.com/d/topic/python-relatorio/XWseheXupNs/discussion

Skills:

Knowledge in Python and XML is required

Difficulty Level:

Intermediary

Potential mentors:

@ced
@nicoe
@kstenger
@pokoli