[Ovmsdev] Refactoring MODEM/SIMCOM for v3.3

[Craig Leres]

I just tried updating my dev module from 3.2.014-103-gcf346399-dirty to 
3.2.015-151-g3377eed0-dirty and I find the wifi stops working after a 
few minutes. Right after a boot I connect to the webserver but once I 
submit a page I start getting timeouts. I can also connect to the ssh 
port but ssh -v doesn't show any negotiation. I reverted to the older 
version and it works again.

My only local changes are to ifdef out some simcom_7600.cpp init code so 
I can work on trying figure out the correct init sequence.

		Craig