Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/os_win32.txt b/runtime/doc/os_win32.txt
index bb1dbdc..8f4d30b 100644
--- a/runtime/doc/os_win32.txt
+++ b/runtime/doc/os_win32.txt
@@ -1,4 +1,4 @@
-*os_win32.txt*  For Vim version 8.0.  Last change: 2017 Mar 21
+*os_win32.txt*  For Vim version 8.1.  Last change: 2017 Mar 21
 
 
 		  VIM REFERENCE MANUAL    by George Reilly