Allow train to run with a timeout

[dwarfland]

for CITestServer, id love to be able to start a .train run with a timeout (say 2hours) specified in seconds via the commandline (-t, --timeout). if the timeout it hit, Train would terminate the current action (if its a shel.exec, including terminating the bad process), and exit properly, including writing a proper log, with "termination due to timeout" as the failure info in the log.

this would beam me having to kill Train.exe from the outside, losing the log.