This release adds streaming support to the QueryResult (thanks to @nappa85, @dodomorandi). Namely it adds two new methods:

• QueryResult::stream – to stream the current result set,
• QueryResult::stream_and_drop – to stream the current result set and ignore subsequent sets.

Also this release adds a few convenience methods into Query and Queryable traits (they are based on QueryResult::stream_and_drop):

• Query::stream – executes a query/statement and streams the first result set ignoring subsequent sets,
• Queryable::query_stream – performs a query and streams the first result set ignoring subsequent sets,
• Queryable::exec_stream – executes a statement and streams the first result set ignoring subsequent sets.

(See #166, #90)