Pause 'in' discards frame

The pause 'in' now works slightly differently on the serial and socket
inputs to avoid any unprocessed out of date or inaccurate frames being
read from the inputs buffer after a pause is lifted. The pause 'in' now
allows the input to function normally but discards the frame and clears
the buffer before any processing occurs.
Pause 'all' for full pause

The full pause function is pause = all, this pauses both the input and
output of the interfacer or reporter.
Pause 'in' moved into _process_frame()

As the interfacers are discarding frames when the input is paused, this
code can be located it the _process_frame()  to simplify the read()
methods and reduce duplicated code.
Setting timestamp optional

Removed the need to have the timestamp code in each read() method by
automatically adding it if it is omitted at the start of
_process_frame(). less repetitive code and less mandatory items for
custom interfacers to have. I have left JeeInterfacer with the timestamp
code in read() as an example but it is not required as shown in the
SocketInterfacer. The one SocketInterfacer will now handle submissions
with a timestamp and without.
Revert "Setting timestamp optional"

This reverts commit 19d4e07b2622110a5298f12a114094dcb69bbacd.
Setting timestamp optional (corrected comment)

Setting timestamp optional  Removed the need to have the timestamp code
in each read() method by automatically adding it if it is omitted at the
start of _process_frame(). less repetitive code and less mandatory items
for custom interfacers to have. I have left JeeInterfacer with the
timestamp code in read() as an example but it is not mandatory as shown
in the SocketInterfacer read().
Merge pull request #108 from otherWIP/testing

updates to pause and timestamping