Since we need to maintain backwards compatibility for class constructors we should settle on using method injection instead of constructor injection. I've replaced the `Definition` class we're using with one that doesn't support constructor arguments and added a check for auto_arg addition. Note that we don't check for method existence in the extended container. This is because reflection is unnecessarily expensive and we should avoid it if at all possible.
- src/README.md largely expanded
- tests/README.md expanded
- includes/README.md added
- src/Internal/REAMDE.md added
src/README.md and includes/README.md have TODO placeholders to add
guidelines regarding to actions and filters.