Support native Ink booleans if needed

[maurovanetti]

According to the release notes:

ink now has a proper bool type
Booleans are now supported natively in-engine, but they also implicitly coerce to integers to support old behaviour of true + 1 == 2. This is useful when you want to convert a flag (have you done X) to a counter (how many times have you done X).

Code and documentations should be updated accordingly.

[maurovanetti]

This is also related to #3