Fix lots of warnings reported by Clang.

Mostly potentially lossy implicit conversions in headers (long->int). Also dangling else warnings. Struct/class mismatches.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74473 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/graphics.h

@@ -398,7 +398,7 @@ public:
     void Add(wxColour col, float pos) { Add(wxGraphicsGradientStop(col, pos)); }
 
     // Get the number of stops.
-    unsigned GetCount() const { return m_stops.size(); }
+    size_t GetCount() const { return m_stops.size(); }
 
     // Return the stop at the given index (which must be valid).
     wxGraphicsGradientStop Item(unsigned n) const { return m_stops.at(n); }