Open new Plot Window when OptimizationProblem is changed

Instead of showing all results in a single plot window, EvA2 should open a new plot window for each OptimizationProblem. So when I run DE, PSO and GA against the Sphere problem all results end up in a single graph window and when I run them against Schwefel (or other) a new window will open with the new graphs.

• The graph should get a title with the name of the function
• The legend should only list an abbreviation of the Optimizer and the dimension (maybe params?)
• The graph should simply show f(x) on the y-axis instead of fitness