Zero choice

[sebwas]

Added a possibility to specify a special text for an empty list for example. Also a fix was introduced for if a choice > 2 was used, as that would break the choices.

Now, if three options are specified, it will map the choice as follow:

choice => used index
--------------------
    0  => 0
    1  => 1
    2+ => 2

If only two options are specified, it will use indices:

choice => used index
--------------------
    0  => 1 // Following a '0 cars' thought: 0 cars, 1 car, 2+ cars
    1  => 0
    2+ => 1

I added a test to test for the above mentioned functionality and did not touch the remaining tests to ensure full backwards compatibility.

[coveralls]

Coverage increased (+0.04%) to 91.572% when pulling c2b4297 on sebwas:zero-choice into 328bffc on kazupon:dev.

[kazupon]

Thanks!
That look for good! 👍