Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/usr_42.txt b/runtime/doc/usr_42.txt
index a440d68..1e187e9 100644
--- a/runtime/doc/usr_42.txt
+++ b/runtime/doc/usr_42.txt
@@ -1,4 +1,4 @@
-*usr_42.txt*	For Vim version 8.0.  Last change: 2008 May 05
+*usr_42.txt*	For Vim version 8.1.  Last change: 2008 May 05
 
 		     VIM USER MANUAL - by Bram Moolenaar