[h5] File: convert shared_ptr<T> ptr(...) to make_shared<T>(...)
[h5] Source+Block: Avoid intermediate shared_ptr variable

Makes code shorter!
Block::findSources: Use range-based for loop
Section: replace iter based loops with ranged-based one
Merge pull request #288 from gicmo/code_cleanup

Code cleanup: shared_ptr obj creation and range-base for loops

Thanks, nice cleanup