fix android view resize on keyboard, also allow all device orientations

src/app.h

@@ -79,6 +79,8 @@ public:
     std::string doc_filename;
     bool has_stylus = false;
     bool has_vr = false;
+    float off_x = 0;
+    float off_y = 0;
     float width;
     float height;
     bool keys[256];