Create helper class that converts values into readable strings

[Matthimatiker]

Create a utility class (Stringifier) that is able to convert any value into a readable string.

This should for example be useful if an unexpected argument type is received by a method and the received type/value shall be added to an exception message.

Requirements:

• Arrays should be shown in a simple way: [1, 2, 3], {'a': 'b', 'c': 'd''}
• The class name of an object should be shown: stdClass
• Resource types should be specified further, for example file handles
• It should be possible to stringify exceptions, including all previous exceptions (with appropriate indention)
• Simple types should be converted to readable strings: null, true, false
• Quotes should be added to strings, to distinguish these from other types: "Hello World!"

[Matthimatiker]

The helper class should also be able to deal with closures (at least it should not break).

[Matthimatiker]

Added class Mol_Util_Stringifier that provides the methods stringify() and stringifyException().

Currently, stringify() is mostly used to create representations of invalid arguments. These representations are added to exception messages.