No warning with invalid confidence level

[VLDrenth]

There is no error or warning message shown when the confidence level is set outside 0 or 1. In this case the confidence level seen in the output (and exports) is set at 95%. It would probably be good to have a warning message when an invalid confidence level is selected.

[aalfons]

The fix should be in two parts:

1. Package robmed should show a warning in this case.
2. The GUI should not allow to set the confidence level outside a reasonable range, for instance the interval [0.9, 1).

[aalfons]

Part 1. is now fixed in package robmed.