Trigger event test

Putting some test just to make the structure of tests works. I'm
changing the type of the trigger event as well from
CONSTANT_EXPRESSION_SYMBOL ('I') to TRIGGER_EVENT_SYMBOL ('T').
Stacked Symbol class test

Probably this call will vanish in the future. I do not see the point
of add function in Symbol and `stacked' symbols...
Tests of parameter class

Basically this is a stacked class that holds the concept of be a
parameter. So, I really don't need test here because I already
tested in stacked symbol class.
Array class' test

Maybe it is more a TODO than a comment. The function setTail do not
need receive the line because the Symbol class holds this information.
Implementing functor test cases

When I was implementing the test of functor class, I saw
that it do not hold the parameter and annotation objects.
So, a refactory to include it happened.
Improving coverate by removing useless lines

Removed lines that aren't executed. This lines were there
just to make the compiler do not generate warning log. It
do not generate warning when I removed so I'm trying to
submit it to Drone.IO and see what happens.