Fix off-by-one in interpolation of extending gravity line

Currently it interpolates it based on the current state of game.swngame,
but when game.swngame changes the interpolation doesn't know that it has
JUST changed or anything. So add a kludge variable to fix this
off-by-one.

desktop_version/src/Graphics.cpp

@@ -137,6 +137,8 @@ void Graphics::init()
     col_tr = 0;
     col_tg = 0;
     col_tb = 0;
+
+    kludgeswnlinewidth = false;
 }
 
 int Graphics::font_idx(uint32_t ch) {
@@ -1649,7 +1651,7 @@ void Graphics::drawentities()
         case 5:    //Horizontal Line
         {
             int oldw = obj.entities[i].w;
-            if (game.swngame == 3 && obj.getlineat(84 - 32) == i)
+            if ((game.swngame == 3 || kludgeswnlinewidth) && obj.getlineat(84 - 32) == i)
             {
                 oldw -= 24;
             }