[reSIProcate] resip::SipStack "stateless" parameter

[Adam Roach]

Currently, the resip::SipStack class constructor has a boolean parameter 
called "stateless." As far as I can determine, this parameter isn't 
stored anywhere, which means that is has no effect on operation of the 
stack. It is not documented in the doxygen comment block for the 
constructor, so I would guess that it is probably vestigial, from an 
abandoned design direction (as opposed to intended for future work).

Unless someone objects, I will be taking steps that will ultimately 
result in the repurposing of this parameter to indicate whether sigcomp 
compression is to be enabled on the stack. It will continue to be a 
boolean parameter, so the (also undocumented) socketFunc parameter will 
be accessible in the exact same way as it was before.

/a