Custom scaling for failure rates

The failure rate entered in all modes (i.e. user defined, catalog, sum of failure modes) can now be scaled according to a custom mathematical expression. This might be useful if failure rates come from different sources, if they need to be adjusted based on field measurements or if just a fraction of the failure rate applies since only part of a component is in use.

Propagate safety related flag

A button has been added to the property view that allows to easily propagate the "safety related" flag to all contained elements.