(/=) SyntheticClock

Merged the two classes to sort messages in one with its interface,
created an interface for the display of the messages

(-) LamportSorting
(-)VectorClockSorting

(+)ChatDisplayMessageInterface
(+)SyntheticClock
(+)SyntheticClockInterface

(/=) ChatLogic
correspondingly to changes above

(/=) ChatLogicFactory, RegisterActivity,
fixed two little bugs