Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/help.txt b/runtime/doc/help.txt
index 527b8f7..4c8eb94 100644
--- a/runtime/doc/help.txt
+++ b/runtime/doc/help.txt
@@ -1,4 +1,4 @@
-*help.txt*	For Vim version 8.0.  Last change: 2017 Oct 28
+*help.txt*	For Vim version 8.1.  Last change: 2017 Oct 28
 
 			VIM - main help file
 									 k