Refactor MainWindow Part 2 of 5

Decoupled classes from MainWindow to reference Context
and Athlete (and introduced a couple of new headers).

We no longer pass around a MainWindow pointer to children
but pass a context instead.

There are still a few pieces left in MainWindow that need
to move to a better place;
    * Setting/clearing filter selection
    * Working with Intervals
    * Adding/Deleting Rides
    * Save on Exit

As mentioned previously there are lots of other parts to
this refactor left to do;
    * break MainWindow Gui elements into Toolbar and Views

    * migrate from RideItem and Ridelist to ActivityCollection
      and Activity classes that are not tied into gui elements.

    * introduce Application Context and AthleteCollection

src/RideWindow.cpp

@@ -17,6 +17,7 @@
  */
 
 #include "RideWindow.h"
+#include "RideItem.h"
 #include "RealtimeData.h"
 #include "JsonRideFile.h"
 
@@ -52,17 +53,16 @@ void RideWindow::loadRide()
                             this, SLOT(addJSObjects()));
     view->setPage(page);
     // used for testing...
-    RiderBridge* tr = new RealtimeRider(main);
+    RiderBridge* tr = new RealtimeRider(context);
     tr->setRide(ride);
     rider = tr;
     addJSObjects();
 }
 
-RideWindow::RideWindow(MainWindow * _main) :
-    GcWindow(_main),
+RideWindow::RideWindow(Context *context) :
+    GcWindow(context),
     rideLoaded(false)
 {
-    main = _main;
     setInstanceName("Ride Window");
     view = new QWebView();
     QVBoxLayout *layout = new QVBoxLayout();