Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/change.txt b/runtime/doc/change.txt
index ffc5abd..05c18e6 100644
--- a/runtime/doc/change.txt
+++ b/runtime/doc/change.txt
@@ -1,4 +1,4 @@
-*change.txt*    For Vim version 8.0.  Last change: 2018 May 12
+*change.txt*    For Vim version 8.1.  Last change: 2018 May 12
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar