patch 8.2.2658: :for cannot loop over a string

Problem:    :for cannot loop over a string.
Solution:   Accept a string argument and iterate over its characters.
diff --git a/src/version.c b/src/version.c
index e09153f..a7406d9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2658,
+/**/
     2657,
 /**/
     2656,