v0.5.0

• Fix duration display in iCal (thanks to @j-veylop)
• new feature "copy all headers". no GUI for it, only a keyboard shortcut.
• new event provider: stack exchange site votes.
• icons: properly invert when using a dark theme
• new preferences window: dark theme option+skip weekends on prev/next option
• gitlab would fail parsing changes in some cases, fixed that
• various code improvements