Modify the design to allow several json files in a single ParserOutput

[omishali]

• Sometimes, we would like a single parser to produce more that one json outputs (e.g., the parser for Tanach and Mefarshim). This means that, e.g., some json objects will be flushed to json "1.json" where other objects will be flushed to "2.json".
• Each jsonObject* method, e.g., jsonObjectAdd(...) should have an additional (first) string parameter that identifies the json where the object should eventually be flushed into.
• Note that we still have a single ParserOutput, however it may include data about several jsons.