improve documentation for generateIIASASubmission, harmonize logFile use

[orichters]

Purpose of this PR

• address fix and factor out generateIIASASubmission() functionality to be used as general REMIND output filter for submissions #219
• improve documentation for generateIIASASubmission
• For logFile: If a parameter outputDirectory exist, write the log into this folder if logFile is just a pure filename. If it contains a more complete path such as ./log.txt, use this one
• allow to switch off with logFile = FALSE. Still, not all messages are caught at the moment.