Server: Be able to handle multiple clients
Server: Run symulation and receive clients message symultaneously

Create separate thread for running symulation, server is listening
on main thread
Server: accept controlers connections and receive messages from them

At the same time be able to sevice visualisers and to run symulation
Server: Add synchornization methods to Symulation

This methods allows Symulation's objects to used and changed from only
one thread at the time
Create base class representing client's command
Server: implement controler motor speed change command
Server: Implement collision detection and resolving
Merge branch 'multiclient'

Conflicts:
	KheperRobotSymulation.sdf
	KheperRobotSymulation.v12.suo
	KheperRobotSymulation/KheperRobotSymulation.vcxproj.filters
	KheperRobotSymulation/Symulation.h
	KheperRobotSymulation/main.cpp