Fix compiler warnings

All are harmless but for the sake of clarity have
fixed them all bar a couple;

- Lucene grumbles about signed/unsigned conversion which
  is/isn't valid depending upon the version of CLucene you
  compile with. Either way it is harmless.

- QxtScheduleView has a bunch of issues, but since it is a
  third party widget its better to leave it unchanged.

src/PowerHist.cpp

@@ -43,6 +43,7 @@
 #include "LTMCanvasPicker.h" // for tooltip
 
 PowerHist::PowerHist(MainWindow *mainWindow):
+    minX(0),
     rideItem(NULL),
     mainWindow(mainWindow),
     series(RideFile::watts),
@@ -52,7 +53,6 @@ PowerHist::PowerHist(MainWindow *mainWindow):
     binw(3),
     withz(true),
     dt(1),
-    minX(0),
     absolutetime(true),
     cache(NULL),
     source(Ride)