Solidity function AST nodes get documentation attribute

Solidity AST nodes get the documentation string attribute if the comment above the function matches the NATspec format (3 slashes for now).

I am not really sure I like the fact that having an empty documentation string and having no documentation string can't be differentiated at the moment. Perhaps this should be fixed. Comments are welcome.
Yeah that is correct. As long as we don't need to hold the skippedComment tokens until a next skippedComment comes then we can be doing this. The current implementation remembers the last skipped comment untils a next one comes along.

But we don't really need this so it's going away.