Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/READMEdir/README_mac.txt b/READMEdir/README_mac.txt
index cdef1a2..d76a11a 100644
--- a/READMEdir/README_mac.txt
+++ b/READMEdir/README_mac.txt
@@ -1,4 +1,4 @@
-README_mac.txt for version 8.0 of Vim: Vi IMproved.
+README_mac.txt for version 8.1 of Vim: Vi IMproved.
 
 This file explains the installation of Vim on Macintosh systems.
 See "README.txt" for general information about Vim.