small readability improvements

- better readability of code (uppercase constants, function curly bracket on new line, removed old commented code…)
- fixed comments to match phpDoc syntax
- unambiguous construct
- default return type from api is now object, not assoc
- method to change api return type
- added new calling of api through magic function with format package_method(params) e.g. $LastFM->track_getInfo($params);