Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/intro.txt b/runtime/doc/intro.txt
index 0f84934..8325bb3 100644
--- a/runtime/doc/intro.txt
+++ b/runtime/doc/intro.txt
@@ -1,4 +1,4 @@
-*intro.txt*     For Vim version 8.0.  Last change: 2018 Jan 24
+*intro.txt*     For Vim version 8.1.  Last change: 2018 Jan 24
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar