patch 8.2.0747: cannot forcefully close all popups

Problem:    Cannot forcefully close all popups.
Solution:   Add the "force" argument to popup_clear().  Use it after running a
            test.  Put back the check for a popup when editing a file.
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 1493291..c010116 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -704,7 +704,7 @@
 			},
     {"popup_atcursor",	2, 2, FEARG_1,	  ret_number,	PROP_FUNC(f_popup_atcursor)},
     {"popup_beval",	2, 2, FEARG_1,	  ret_number,	PROP_FUNC(f_popup_beval)},
-    {"popup_clear",	0, 0, 0,	  ret_void,	PROP_FUNC(f_popup_clear)},
+    {"popup_clear",	0, 1, 0,	  ret_void,	PROP_FUNC(f_popup_clear)},
     {"popup_close",	1, 2, FEARG_1,	  ret_void,	PROP_FUNC(f_popup_close)},
     {"popup_create",	2, 2, FEARG_1,	  ret_number,	PROP_FUNC(f_popup_create)},
     {"popup_dialog",	2, 2, FEARG_1,	  ret_number,	PROP_FUNC(f_popup_dialog)},