Chat reform: - reduce code duplication by determining the proper chat class dynamically and storing it in an nsv - move static content in the resources path. Serving them is now independent from the mounted xowiki path - get rid of the ajax url path
Give xowiki chat also some kind of nice skin and centralize css retrieval
TODO: something smarter can be done in order to retrieve the proper css, based e.g. on theme, chat skin (to be implemented) etc. To be discussed is some way to resolve resources based on the theme.