Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/version4.txt b/runtime/doc/version4.txt
index c2b0f9c..3990a4b 100644
--- a/runtime/doc/version4.txt
+++ b/runtime/doc/version4.txt
@@ -1,4 +1,4 @@
-*version4.txt*  For Vim version 8.0.  Last change: 2006 Apr 24
+*version4.txt*  For Vim version 8.1.  Last change: 2006 Apr 24
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar