main.cpp
  
                           Splits Two Threads
  
                      (1)                     (2)
  
    +-------------------+                      +------------------------+ 
    | Thread 1          |                      | Thread 2               |
    | IMS_MOOSApp       |                      | fget(c) in main.cpp    |
    |                   |                      |                        |
    | interacts w/MOOS  |                      | interacts w/USER       |
    |                   |                      |                        |
    |                   |                      |                        |
    | has-a: IMS_Model  |                      | has-a: IMS_Model       |
    +-------------------+                      +------------------------+ 
                         \                    /
(1) Init IMS_Model from   \                  /  (1) Send handleChar(c)
    .moos params           \                /       cmds to IMS_MODEL  
(2) Send vehicle actuator   \              /
    cmds from mailbox        \            /              
(3) Send Sim global           V          V          
    params from        +-----------------------+
    MOOS mailbox       | IMS_Model             |
                       |                       |
                       |                       |
                       | has-a: SimEngine      |
                       | has-a: Vstate         |
                       +-----------------------+