[TASK] Sanitise legacy configuration support
[TASK] Improve performance of page template set resolve logic

By reordering, it's ensured that methods which are quite high in resource consumption are absolutely only called upon when needed.
[TASK] Sanitise cache key declaration
[TASK] Undo changes from optimisation with bad effect
Merge pull request #65 from NamelessCoder/legacysupport

[TASK] Sanitise legacy configuration support