log files in xspec

Fixed bug that was adding a "#" to the next line instead of the current line of log file output. This is a partial fix to issue 1024. Input when setting parameter values (in model or newpar) is still not echoed to the log file - problem is in ModelContainer::setParameterFromPrompt.

Update: had to back this change out because it doesn't work with tcerr, which is not buffered and hence passes one character at a time to TclIO::write. Craig worked out how to fix xsLog.cxx to fix the problem.