Support for remote execution of shell jobs

This improvement implements the following features:

• <script language=".."> and <process file=".."> are supported for remote execution. Filenames are interpreted on the remote host.
• Remote execution makes use of a separate TCP connection that is maintaned during the process lifetime. For Windows the restrictions concerning the number of TCP connections (30) apply.
• Environment Variables, Task and Order parameters are handed over to remotely executed tasks. Environment variables are used from the remote server system.
• The local Job Scheduler is immediately notified should a process terminate.
• A log file as configured by <process log_file = ".."/> is fetched from a remote host and added to the local log.
• Order parameters are returned after remote execution.
• kill and timeout are supported.
• output to stdout and stderr is added to the local log file.
• Exit codes and Unix signals are returned.