Allocator: rewritten to exploit memory slices
String: a new class to hold the size and the pointer to a memory area

Typically this class is used to construct strings. Thus, the memory area
contains embedded zero at the end, like the C strings. However, it is
not counted to the length of the string, and the string itself may
contain zeros.
Types: added Size8
List: fixed ListIterator to hold pointer to generic types
Object: a new class to represent objects that are owned by an actor

Also, the Object class provides advanced memory handling using the
allocator of the current dispatcher by overwriting new and delete
operators.
Actor: added Object to be super class
FactoryMethod: modified to use fixed type for the argument
Dispatcher: added support for allocators

Recycles allocators to ensure that sizes of allocations and deallocation
are spread across different dispatchers.
Source & IoSource: removed handlers and restructured responsibilities