[Cooja] Reimplementation of the IPAddress interface

I put some effort in creating a new IPAddress interface
that resolves many issues I encountered with the current one.

New features:
* extended interface
* Shows all IPv6 addresses of a mote
* Shows link local IP in visualizer
* Improved memory management
* New RFC5952-compliant IPv6 address shortening routine

Note: Also added the method getVariableSize() to AddressMemory as this information is already available in the emulators and might help to simplify some operations.