Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/READMEdir/README_extra.txt b/READMEdir/README_extra.txt
index c42043e..ce629b2 100644
--- a/READMEdir/README_extra.txt
+++ b/READMEdir/README_extra.txt
@@ -1,4 +1,4 @@
-README_extra.txt for version 8.0 of Vim: Vi IMproved.
+README_extra.txt for version 8.1 of Vim: Vi IMproved.
 
 These extra files of Vim are for special purposes.  This README explains what
 the files are for.  For general information about Vim, see the "README.txt"