Shape-Out 2.0.0a24

• implemented polygon filters
• condense context menus, add export context menu to all plots
• add computation of Young's modulus and crosstalk correction
• add user-defined fluorescence labels in QuickView
• add legend to trace in QuickView
• populate metadata panel
• implement multiple subplots per plot, plot title, plot labels,
  legend, and event count
• refactor data model
• functionalize buttons in analysis view
• correctly handle datasets with different sets of features