code: remove useless as(not null)

Signed-off-by: Jean Privat <jean@pryen.org>
typing: warn for useless .as(not null)

Signed-off-by: Jean Privat <jean@pryen.org>
comp: skip .as(not null) on not pointer values

Signed-off-by: Jean Privat <jean@pryen.org>
tests: inmprove base_as_notnull*.nit and update tests

Signed-off-by: Jean Privat <jean@pryen.org>
Merge 'origin/master' into fix-asnotnull to supress new warnings
neo4j: remove some as(notnull) to supress warnings

Signed-off-by: Jean Privat <jean@pryen.org>
Merge: Fix asnotnull

Add warnings on useless as(not null)  (one less TODO) and fix the bug on non-null primitives.

Fixes #589

Pull-Request: #591
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>