Add the settabvar() and gettabvar() functions.
Various runtime file updates.
diff --git a/runtime/doc/usr_27.txt b/runtime/doc/usr_27.txt
index aa24a26..1098f44 100644
--- a/runtime/doc/usr_27.txt
+++ b/runtime/doc/usr_27.txt
@@ -77,7 +77,7 @@
 
 	Note:
 	The use of "\" items in search patterns depends on the 'magic' option.
-	In this chapters we will assume 'magic' is on, because that is the
+	In this chapter we will assume 'magic' is on, because that is the
 	standard and recommended setting.  If you would change 'magic', many
 	search patterns would suddenly become invalid.