added buttons for ordering of dists. and nvls

- also removed the previous dropdown-menus
added default axis orientation for nvl/dist

- also added the utility to read SortModeDist and SortModeNVL from
config
- added default values for those to gui.properties
reworked interval-panel in menubar for dist/nvl

- also added a button to show/hide grid for x2 on
multiscalar-visualizers
- also added some missing tooltips
added show/hide logic for y1/y2
little code cleanup and comments added