Redefine, rewrite and refactor any renderer stuff

[phorward]

The current renderer stuff is a buggy mess of ugly, old code.
It should be entirely redesigned with a clear and straight concept.

Some issues with the current implementation:

• Optional function _postProcessAppObj used by json and xml should be converted into a standardized Index-module
• The renderers are currently constructed from the renders folder. This brings in several disadvantages, as the declared symbols are bad to distinguish.
• It is possible to register a module called html or json, with messes up with the specific renderer without any hint or error message
• A render refers to a module and a module to a renderer. This makes it impossible to instantiate each module and each renderer only once
• The concept of defining a module specific renderer, like with user, is nowhere else used in any ViUR project. By the concept of ActionSkels, module-specific renders become obsolete and therefore the possibility should entirely be removed.
• Enabling a renderer with Module.json = True is absolutely ugly
• jinjaGlobalFunction/jinjaGlobalFilter should be defined differently

Issue relates to #1071.