A candidate patch to Github issue #15. Three problems related to TRACE might be corrected by this patch.
Problem 1: the same Pajé container (corresponding to the same MSG_process) could be destroyed more than once by the current TRACE logic.
Fix: A safer mechanism avoids multiple destroys of the same container.
Potential problem: the current TRACE logic might be bugged and this fix may only hide the problem.
Problem 2: the Pajé container (corresponding to a MSG_process) was created after the simcall_process_create although the simcall might not return the flow control.
Fix: The Pajé container is now created before the simcall_process_create (the future SIMIX process ID is hacked thanks to SIMIX_process_get_maxpid())
Code redundancy: The function TRACE_msg_process_end destroyed the process container in the exact same way as it was done in TRACE_msg_process_destroy.
Fix: the TRACE_msg_process_destroy function is now called instead.
