Added NrrwRgn plugin

vim/bundle/chrisbra-NrrwRgn/todo.txt

@@ -0,0 +1,13 @@
+- Implement MultiEditing for :NRM
+  (see https://github.com/felixr/vim-multiedit/blob/master/plugin/multiedit.vim
+   and http://blog.felixriedel.com/2012/06/multi-editing-in-vim/)
+
+- When disabling Narrowing using :NRN and one quits the buffer,
+  should the highlighting be removed? (it doesn't yet)
+
+- I really need some tests, like:
+  * Visual Narrowing
+  * Narrowing 1 Region
+  * Narrowing several independent regions with setting the g:nrrw_rgn_protect
+    variable
+  * Multi line narrowing