Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/cmdline.txt b/runtime/doc/cmdline.txt
index d1f949d..d2c8196 100644
--- a/runtime/doc/cmdline.txt
+++ b/runtime/doc/cmdline.txt
@@ -1,4 +1,4 @@
-*cmdline.txt*   For Vim version 8.0.  Last change: 2018 May 14
+*cmdline.txt*   For Vim version 8.1.  Last change: 2018 May 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar