AQL classes have the highest priority for name resolution

[pjeanjean]

The following code fails:

behavior testale_behavior;

class Expression {
	int a := 0;
}

open class ClassA {
	@main
	def void run() {
		Expression.create().a.log();
	}
}

The issue is that a class named Expression is also defined in Acceleo, and it is the one actually referenced here.
Opening a class Expression defined in the associated meta-model without its qualified name would also fail.

Ideally, the user's classes should have a higher priority when not using full qualified names.

[echebbi]

Related to #146 and #151.

In my opinion we shouldn't even match AQL EClasses unless the AQL EPackage has been explicitly added to the environment.