Add channelMode to QProcess::startDetached

When one does a QProcess::startDetached, the new process' stdout is printed to the original process' terminal. QProcess::start does not exhibit this problem. It has probably been with us for a while, so perhaps nothing can be done. This is specific to linux; on Windows (if I add a CONFIG += console), the newly created process will bring up a new terminal.

Resolution: Unfortunately, because this behavior has been in Qt for so long, we cannot change this behavior.

Changed to suggestion: Could we possibly add an enum to the ProcessChannelMode that would allow startDetached to reopen stdout/stderr to /dev/null (opposite of ForwardedChannels)? This way the original functionality will be intact and startDetached can be modified to operate more like it's documentation ("On Unix, the started process will run in its own session and act like a daemon.")

Update: Investigate further.