BASS, VerbCoin: comment module functions and properties

[ivan-mogilko]

This refers to BASS and VerbCoin, they both have extra script modules with API that controls interface behavior, but this API is not documented in code at all.

I suggest to add a short comment per each function and property, similar to how it's done in the standard API (do we have to use C#-style triple slash for autocomplete? I never investigated how that works), and also a more in-depth explanation of the module on top of the header.