Implements a static checker based on the K3 interpreter

• Add a popup action to manually trigger a check of the static contracts

• Add a builder to automatically trigger the check on *.abs file change (enabled/disable is possible at the project level, cf. popup)

• failed contract are reported in the console and using eclipse markers.

• Eclipse marker are set on the first contract parameter.

Refactor vm concepts to use the new Guard concept introduced in #150 (closed)

Additionally, this MR fixes the implementation of the evalMember for Attribute

Closes #156 (closed)