Introducing parser levels, defining the order of processing

Parser can define a field level which determines which order they will be run in, as requested by #668 (closed) . The default value is 0. Level 0 parsers are run first, then level 1, then level 2, and so on. The code defined in Upload and Calc for special handling of the phonopy parser is therefore also removed (the functionality defined there should be moved to the parser instead).