patch 8.1.1410: popup_move() is not implemented yet

Problem:    Popup_move() is not implemented yet.
Solution:   Implement it. (Yasuhiro Matsumoto, closes #4441)  Improve the
            positioning and resizing.
diff --git a/src/structs.h b/src/structs.h
index 925bf03..07dc7e3 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -2873,8 +2873,12 @@
 #ifdef FEAT_TEXT_PROP
     int		w_popup_flags;	    // PFL_ values
     int		w_zindex;
+    int		w_minheight;	    // "minheight" for popup window
+    int		w_minwidth;	    // "minwidth" for popup window
     int		w_maxheight;	    // "maxheight" for popup window
     int		w_maxwidth;	    // "maxwidth" for popup window
+    int		w_wantline;	    // "line" for popup window
+    int		w_wantcol;	    // "col" for popup window
 # if defined(FEAT_TIMERS)
     timer_T	*w_popup_timer;	    // timer for closing popup window
 # endif