templater: introduce resourcemapper class A couple more functions will be added later to work around nested mapping bugs such as the issue 5612.

log: do no expect templateresources() returning a dict The resources dict will be replaced with new resource mapper object, which won't implement __getitem__(key). Share the whole resources object with _graphnodeformater() to make porting easier.

templatekw: mark _showlist() as deprecated (API) .. api:: ``templatekw._showlist()`` is deprecated in favor of ``templateutil._showcompatlist()``, which takes ``context`` in place of ``templ``.

templater: drop 'templ' from resources dict Partially resolves cycle, templ -> context -> templ. This will make it easier to replace the resources dict with new immutable resource mapper interface.

templatekw: stop using _showlist() which is about to be deprecated Use the new context-based API instead.

templater: use template context to render old-style list template Prepares for dropping the 'templ' resource. This means old-style list templates are processed by the same engine class as the one for the list node. I think that's fine since templates for the same list should be tightly coupled, and I believe the extension point for the engine classes isn't actually used. Now templatekw._showlist() is a compatibility wrapper for _showcompatlist(), and will be deprecated soon. The function is still marked as private since I plan to change the interface to get rid of closures capturing context and mapping.