privat/nit — pull request #759 by privat (2014-09-19 20:06:09+00:00)
Title: Add and improve warnings

* Add tags (labels) for warnings. could be used by Jenkins or other tools to group warnings
* Add second-level warnings, called "advice", used to limit warning inflation a la java
* Add new warnings
* missing doc
* unread local variable
* useless empty init
* useless attribute type <- was already present, but made a advice, instead of a warnings.

Close #722