Logging errors in core

[ralfw]

All calls to the ForceFeedbackMachine are now wrapped so that any exceptions will be caught and logged to a global error log (in the user's root folder): .forcefeedbackprogramming.log

The logger Log{} is public an can be used by the frontend too.

If an exception is thrown during creation of feedback only a red background color is returned as visual feedback in addition to writing a log entry.