Add Response-Time statistics for each known mgcp message-type.
Fix a few bugs and remove trailing whitespace.
Use "gdouble" for printing time-values and calculating the
average. It is easier to use and shouldn't overflow on big
trace files like "guint32".
Move some functions for time statistics into the new file
timestats.c in the main directory. This code may be useful in
the rpc and smb rtt-taps as well.
svn path=/trunk/; revision=7469
Guy Harris