Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/os_390.txt b/runtime/doc/os_390.txt
index 118df6f..5b4b9f7 100644
--- a/runtime/doc/os_390.txt
+++ b/runtime/doc/os_390.txt
@@ -1,4 +1,4 @@
-*os_390.txt*    For Vim version 8.0.  Last change: 2016 Feb 27
+*os_390.txt*    For Vim version 8.1.  Last change: 2016 Feb 27
 
 
 		  VIM REFERENCE MANUAL	  by Ralf Schandl