Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/if_sniff.txt b/runtime/doc/if_sniff.txt
index d4488c9..cf6ed1c 100644
--- a/runtime/doc/if_sniff.txt
+++ b/runtime/doc/if_sniff.txt
@@ -1,4 +1,4 @@
-*if_sniff.txt*	For Vim version 8.0.  Last change: 2016 Feb 27
+*if_sniff.txt*	For Vim version 8.1.  Last change: 2016 Feb 27
 
 
 		  VIM REFERENCE MANUAL