GammaLib

This is actually a GammaLib issue, since debug mode was not switched on at the GApplication level before writing the header.

I added the debugging functionality to GApplication::logFileOpen:

    // Open logger only if filename is non-empty
    if (!log_filename().empty()) {

        // Initialise the application logger
        log.open(log_filename(), clobber);

        // If we're in debug mode then all output is also dumped on the
        // screen
        if (logDebug()) {
            log.cout(true);
        }

        // Write header into log file
        log_header();

    } // endif: file name was not empty

Merged into devel.