This MR introduces a few extensions to the typifier, allowing it to infer types for a wider range of more complex expressions.
In particular, the typing of array literals and array declaration is improved significantly.
Allow nested type contexts to be deferred by linking them to their parent contexts via inference hooks
Introduce a system of type hints and their propagation through inference hooks in order to
resolve type contexts from incomplete type information
propagate fallback-to-default behaviour to nested contexts
(possible future applications)
Use the above to refactor and extend the type inference of array literals and subscripts:
Array literals now fall back to the default type if no array type is known
Inline array literals can now inherit their type from the enclosing expression's type context
Apply the default numeric data type to arguments of PsCast and relationals if the argument type could not be inferred
