Vim 8.1 release

Update version number and information.  Fix a couple of tests.
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index b05a479..01c2d0e 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1,4 +1,4 @@
-*options.txt*	For Vim version 8.0.  Last change: 2018 May 15
+*options.txt*	For Vim version 8.1.  Last change: 2018 May 15
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar