Merge: phase: Introduction of new hook method

This pr introduces a new hook method in the execution of the `process_nmodule_after_phases` phases. This method makes it possible to analyze each module again after the execution of all phases in order to benefit from the information of the whole program.

This method is useful in the context of contracts. Example:

```nit
module b

redef class A
	redef fun foo
	is
		ensure(result > 2)
	do
		return 2
	end
end

var a = new A
a.bar
```
```nit
module a

class A
	fun foo: Int do
		return 1
	end

	fun bar do
		self.foo
	end
end
```

Actually, when you call the foo property in the bar method, no contract is called, while a postcondition was added by refinement in the `b` module. In fact it was not possible to call the contract face because it was not yet introduced during the analysis of module `a`. It is now possible to re-analyze all the modules to make the redirection once all the information are known.

Pull-Request: #2828