Code maintenance

* adjust some comments
* adjust some test method names
Ensure that no unexpected perso is loaded

This change ensures that loading the simulator is aborted if the
indicated perso can not be loaded. This behavior is usefull to ensure
that the user does not operate on a different perso than expected. It
was default behavior up to some commit in the near past and should not
have been changed in the first place.
PersoSim: fixed return value
PersoSimTest: fixed test cases - if file or encoding of personalization
is invalid, the corresponding exception is dealt with in the called
method. As a result to be tested the simulator won't start unless a
valid personalization is provided.