Initialize session variable - avoiding possible garbage in calc_timestamp(). Reduce assumptions made in add_ms(), and don't permit tv_usec to exceed 999999.
Initialize session variable - avoiding possible garbage in calc_timestamp(). Reduce assumptions made in add_ms(), and don't permit tv_usec to exceed 999999.

git-svn-id: 9ed0004971709408f906b8bdafa7f98a7bcab630@1296 f854266a-e20d-0410-a9be-8852184c940f

zlargon/iaxclient,zlargon/iaxclient,zlargon/iaxclient,zlargon/iaxclient,zlargon/iaxclient