make EngineTracer print current datetime

darcs-hash:20090312101154-b2873-42475184681a0fc7c9aa7c76850d1f135ca7a8ef
add scripts/sip_im_session2.py (based on Session)

darcs-hash:20090312101251-b2873-2c6473bc147d3c7c6a8d551a1306bee65adea506
Check if SDP array items are None in core

darcs-hash:20090312101556-58103-96517279338895b346717ea6f53de55323a64d91