Changed to decimal precision for improved replay accuracy.
For inter packet time > 1s, the integer precision would set up rate as 0
instead of 0.x - this also gets fixed by this change.
Looks like starting somewhere in Wireshark 2.x, when we give -x to
tshark, we also need to explicitly give -P to include the one-line
summary of the packet. This one-line summary is used in the diff to find
out which packets experienced a diff.
Earlier the default value for num_packets was 1 and the imported streams
therefore also had the same. However, when the default value got changed
to 10, the num_packets for imported streams should have been explicitly
set to 1 - this was missed out and has been fixed now
