Multple traits selector

If a table with multiple traits is loaded for DACE or CACE (and PIC and Pagel94?), the user can select the traits on which the analysis should be run.

Needs a validator for type of data: If DACE was chosen and the trait column contains floating point numbers the user is warned with the warning "Continuous trait will be interpreted as discrete character. Do you want to continue? [Yes] [Cancel]", [Cancel] deselects the trait. Both return the user to the selector panel.