added a working y-axis button for multiscalar vis.

- also renamed "metricvisualizer" package to "visualizer"
changing directory now also clears multisc. list
added several features to the legendlist

- legenditem layout reworked
- added different legenditem classes for different types of values that
are plotted
- added button to hide/show graphs in the plot without deleting them
- added button for distr. & nvl-items to select different sort/plot
settings for each item individually
- added second x-axis and a button to change between x1 and x2