Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/pattern.txt b/runtime/doc/pattern.txt
index ead319c..337cbf7 100644
--- a/runtime/doc/pattern.txt
+++ b/runtime/doc/pattern.txt
@@ -1,4 +1,4 @@
-*pattern.txt*   For Vim version 8.0.  Last change: 2018 Mar 13
+*pattern.txt*   For Vim version 8.1.  Last change: 2018 Mar 13
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar