Improve adt test and file structure

[timofeymukha]

Dep #2370

Improves tests for types under src/adt. Some types were not tested at all, some additional tests added for others. Sparse comments on what is tested added.

In the type modules themselves, public is stripped from type definitions instead a list of public : type_name is arranged at the top, declaring the data type inside as a comment. This makes it much easier to find the concrete type necessary for data at hand.

[njansson]

Style comments aside (I'm in favour of having public at the type declaration), I do recall that certain compilers can't declare things public before they are declared, thus this long list has to be moved to before contains, which kind of beats the purpose here.

[timofeymukha]

Style comments aside (I'm in favour of having public at the type declaration), I do recall that certain compilers can't declare things public before they are declared, thus this long list has to be moved to before contains, which kind of beats the purpose here.

OK, I refactored to having tables in the module level docstrings. i would really like to hava quick lookup of the types somewhere