Projection: Support variables

[timotheeguerin]

Projection don't have variables which prevent scenarios like this:

var projectedName = getProjectedName(self, wire);
if(projectedName) {
  self::rename(projectedName);
}

you can always have something like this but this prevent more complex projections

if hasProjectedname(self, wireName) {
  self::rename(getProjectedName(self, wireName));
}

[markcowl]

pri: 2