Improved Season Support

This fixes issues with date range editing in the Metrics controls
and provides support for Season load planning (under development).

Creating and selecting seasons is largely managed within the
Metrics tool. This has not been changed with this patch. Athlete
seasons are now managed as a member of the MainWindow class (although
this will move to an Athlete/Cyclist class when MainWindow is
refactored).

A Season identifier (UUID) has been introduced to enable Seasons to
be referenced independently of their name or date ranges. The LTM
tool now keeps track of changes to Seasons (when new seasons are
created, changed, deleted). Additionally, the Season XML file now
supports storage of a Season Load Plan.

src/GoldenCheetah.cpp

@@ -315,7 +315,8 @@ GcWindow::spotHotSpot(QMouseEvent *e)
     else if (_x >= (_width-borderWidth)) return (Right);
     else if (_y <= borderWidth) return (Top);
     else if (_y >= (_height-borderWidth)) return (Bottom);
-    else return (Move);
+    else if (_y <= contentsMargins().top()) return (Move);
+    else return (None);
 }
 
 void