Fix quit in empty tab

Previous changes to Close() to make it more tab-friendly did not
correctly handle the following scenario:

:tabe
\be
q

Expected result is to show an empty buffer, actual result was to show
last-used buffer from previous tab.

doc/bufexplorer.txt

@@ -1,7 +1,7 @@
-*bufexplorer.txt*              Buffer Explorer       Last Change: 20 Sep 2016
+*bufexplorer.txt*              Buffer Explorer       Last Change: 30 Sep 2016
 
 Buffer Explorer                                *buffer-explorer* *bufexplorer*
-                                Version 7.4.11
+                                Version 7.4.12
 
 Plugin for easily exploring (or browsing) Vim|:buffers|.
 
@@ -253,12 +253,15 @@ The default is 0, so that the size is set by Vim.
 ===============================================================================
 CHANGE LOG                                              *bufexplorer-changelog*
 
+7.4.12   September, 30, 2016
+    - Thanks again to Martin Vuille for several more fixes related to making
+      bufexplorer more tab-friendly.
 7.4.11   September, 20, 2016
-    - Thanks to jpmv27 for reworking the per-tab buffer listing code.  Fix for
-      g:bufExplorerShowTabBuffer is not working correctly and other "gliches"
-      when the ShotTabBuffer option is enabled.  For example old code would not
-      correctly handle adding/deleting a tab that wasn't the highest-numbered
-      tab.
+    - Thanks to Martin Vuille for reworking the per-tab buffer listing code.
+      Fix for g:bufExplorerShowTabBuffer is not working correctly and other
+      "gliches" when the ShotTabBuffer option is enabled.  For example old
+      code would not correctly handle adding/deleting a tab that wasn't the
+      highest-numbered tab.
 7.4.10   August 26, 2016
     - Thanks to buddylindsey for fixing a misspelling in the docs.
 7.4.9    April 01, 2016

plugin/bufexplorer.vim

@@ -36,7 +36,7 @@
 " Name Of File: bufexplorer.vim
 "  Description: Buffer Explorer Vim Plugin
 "   Maintainer: Jeff Lanzarotta (delux256-vim at yahoo dot com)
-" Last Changed: Tuesday, 20 September 2016
+" Last Changed: Friday, 30 September 2016
 "      Version: See g:bufexplorer_version for version number.
 "        Usage: This file should reside in the plugin directory and be
 "               automatically sourced.
@@ -74,7 +74,7 @@ endif
 "1}}}
 
 " Version number
-let g:bufexplorer_version = "7.4.11"
+let g:bufexplorer_version = "7.4.12"
 
 " Plugin Code {{{1
 " Check for Vim version {{{2