Depending on used component classes, created sheetnames in writeOptimizationOutputToExcel() are too long for the excel format

[t-gross]

If output is written to excel by calling writeOptimizationOutputToExcel(), Excel sheet names are constructed including class name and the suffix for variable & dimensions. Some component class names (e.g. the subclass ConversionDynamic) in combination with the variable and dimension exceed the Excel limit of 31 characters.

See also #58

[d00958]

Just for the sake of completeness, this also applies to the ConversionPartLoad subclass.