[Jsbsim-matlab] S-Function Updates

[b m. <bri...@in...>]

Have now tested a second s-function that uses discrete states calculated by JSBSim with very good results.  The simulink model's state outputs exactly match the states calculated by JSBSim.  This seems to work a whole lot better than my previous model that used continuous states that were calculated within the s-function.  Also was able to linearize, though this still needs to be looked at closer.  

My only real problem right now is getting the set-running to set the engine running- it does not seem to be working.  

This should be ready for sharing very soon.  The code needs some housekeeping and some error checking stuff added before its ready.

Brian