ess-Importer: add GUI to the launcher
- Should allow batch-importing multiple saves at once.
- Should integrate with the Character system for save games, i.e. allow importing saves to either a new character or to an existing one.
- An integration with the installation wizard might be possible. If the selected Morrowind directory contains any save files, offer importing them.
- When the importer process wrote anything to stderr, the output should be shown in a warning message pop up.
- When the importer process returned a non-zero exit code, an error message should pop up and the queued imports should be aborted.
(RM-2315 from redmine: created on 2015-01-26 by scrawl ., )