- Added Save Figure button
- Added legend for element positions (turn off via settings)
- Statusbar message now displayed before initalizing pyQtDataViewer

 - Minor renamings for increased readability

      - adopted coloring for better comparison
      - Difference (to mean or iloc[0]) now for all columns correctly done

v2.9c Difference mode x-x.iloc[0] and y-y.iloc[0] selected by default (switchable through setttings menu)

v2.9b plotwindow.py major update: added export data and save figure functionality; added possibility to change font size

v2.8d Plotwindows calculate sliced emittance only after pressing a button; Added OverflowError exception to return_bins method

counter added; counter is increased with each figure.draw(); if counter reaches specific value or labels change: figure gets cleared and axes reinitialized

v2.8c Addressed MemoryError: Separated fig and axs inside maincavas and clear figure inbetween; Constrained layout instead of tight layout. Might also remove bug concerning sizes.

Moved some options from 'help' to new 'settings' menu; Minor renamings and moving of methods according to PEP convention; Elements within mainplot don't get inverted anymore if y-axis is inverted