VZooming Changes

1: Guard zone 8 pixels wide in VRuler to reduce risk of accidental use.
2: VerticalZooming preference, for VRuler zooming, off by default,
3: Enabled Paul's right-click menu in VRuler with some extra
presets (x2 and x0.5)
4: Rearranged some messy code with lots of ifs to use a switch.

Also, with EXPERIMENTAL_HALF_WAVE defined we now get a
'half wave' option in the VRuler menu, that shows the wave top half.
We also use it in collapsed waves (and collapsing and restoring
a WaveTrack will get you back to normal zoom.

src/TrackPanelMouseEvent.h

@@ -18,6 +18,10 @@ class wxSize;
 class TrackPanelCell;
 #include "MemoryX.h"
 
+// This is a hack so that the code that fakes a MOUSE_LEFT_BTN_UP on
+// capture lost doesn't get in the way of handling MOUSE_RIGHT_BTN_UP.
+const int kCaptureLostEventId = 19019;
+
 // Augment a mouse state with information about which track panel cell and
 // sub-rectangle was hit.
 struct TrackPanelMouseState