4.0.0-beta3: Remove custom PrettyPrinter

Improvements

• Strings in default values or constant values are no longer stripped of their quotes and match the pretty-printing rules of PHP Parser. This will allow consumers to more accurately represent values
• Parsing a DocBlock with an invalid tag will no longer result in an exception but instead, generate an object of type InvalidTag containing the exception causing the reason why this could not be properly parsed.