New monthly calendar (#4679)

* Created new Trends-Chart "Planning Calendar"
* Added supporting tools to Colors
* Added notification about changed season
* Updated ManualActivityWizard to optionally take the date as parameter
* Added some new icons for the calendar
* Reading normalized sport from RideItem
* Showing all events from all seasons
* Added chart-setting to configure the first day of the week
* Added chart-setting to show / hide the summary column
* Updated the appearance of planned workouts (orange icon with no background)
* Setting a pixmap next to the cursor while dragging an activity
* Added a weekly summary
* Summary and entries can be configured in chart-settings
* Replaced some material icons (phases, events, generic sport) with
  ones from breeze (https://github.com/KDE/breeze-icons)
* Updated the calendar-navigation-header
* Minor visual updates (no orange icons on blue selection, ...)
* Always showing subsport when creating a completed / planned activity
* Added "Show in Train Mode..." to Calendar

src/Gui/GcWindowRegistry.h

@@ -77,7 +77,8 @@ enum gcwinid {
         LiveMapWebPageWindow = 48,
         OverviewAnalysisBlank=49,
         OverviewTrendsBlank=50,
-        ElevationChart=51
+        ElevationChart=51,
+        Calendar=52
 };
 };
 typedef enum GcWindowTypes::gcwinid GcWinID;