Feature: put into extended sleep with HUP signal.

There are situations when one does not want to be bothered by popups that
complain that no rdesktop process is running or the network folder is not
mounted. Now the script can be told to sleep for two hours by sending it a HUP
signal. It can be told to resume prematurely using the USR1 signal. This is
also documented in the help screen.
Added mov and webm extensions.
Prompt with current day and time prefix.
Removed unused esckey+hash sequence for winlist.
Removed bindings for windows greater than 9.

I hardly ever used those bindings. When necessary the default esckey+' (select)
is good enough for me.
Extended sleep should only be valid once.

After extended sleep return to the default polling interval.
Apart from that, I also changed the log file name to match
the script's name.