Time management : Using of absolute time

Simulation now uses absolute time to compute collision and other event date.
It allows simulation to have more than one dynamic model.
Agent management:Adding of new properties(from/to)

Agents now can use "from" key to specify which agent has sent an event and
"to" key to specify agent that must use this event.
It allows modeler to have more than one active model of the same type in
simulation.