Patch: test/drive_smpp.c

Hi,

This is a patch to test/drive_smpp.c, which I found useful in SMPPbox 
testing, since I do not have a real SMSc connection. It adds external SMS 
submission along with concatenation, if SMS is too large.

drive_smpp is a very nifty tool. It acts as a (FAKE) SMPP SMSc and smsbox 
for MOs with a twist:

drive_smpp->BB->drive_smpp

This is a single instance of dive_smpp connected to bb both as an SMSc and 
as an smsbox. It generates MOs over SMPP to bb, which are then processed by 
BB to smsbox for an sms-service. Except that drive_smpp is connected as an 
smsbox to receive it and provides a default sms-service "Hello World". This 
in turn, is processed by bb back to drive_smpp(SMSc). All these are logged 
and monitored and drive_smpp even provides for TLV testing/support.

If it is accepted I will do an effort to write some documentation about it.

BR,
Nikos