update vimrc_example file

Because of recent work on defaults (see
neovim#2676)

runtime/vimrc_example.vim

@@ -1,21 +1,17 @@
 " An example for a vimrc file.
 "
 " Maintainer:   Bram Moolenaar <Bram@vim.org>
-" Last change:  2014 Nov 05
+" Last change:  2015 Jun 29
 "
 " To use it, copy it to
 "     for Unix:  ~/.vimrc
 "     for MS-DOS and Win32:  $VIM\_vimrc
 
-" allow backspacing over everything in insert mode
-set backspace=indent,eol,start
-
 set backup             " keep a backup file (restore to previous version)
 set undofile           " keep an undo file (undo changes after closing)
 set history=50         " keep 50 lines of command line history
 set ruler              " show the cursor position all the time
 set showcmd            " display incomplete commands
-set incsearch          " do incremental searching
 
 " For Win32 GUI: remove 't' flag from 'guioptions': no tearoff menu entries
 " let &guioptions = substitute(&guioptions, "t", "", "g")
@@ -27,29 +23,18 @@ map Q gq
 " so that you can undo CTRL-U after inserting a line break.
 inoremap <C-U> <C-G>u<C-U>
 
-" In many terminal emulators the mouse works just fine, thus enable it.
-if has('mouse')
-  set mouse=a
-endif
-
 " Switch syntax highlighting on, when the terminal has colors
 " Also switch on highlighting the last used search pattern.
-if &t_Co > 2 || has("gui_running")
-  syntax on
-  set hlsearch
-endif
-
-" Only do this part when compiled with support for autocommands.
-if has("autocmd")
+syntax on
 
-  " Enable file type detection.
-  " Use the default filetype settings, so that mail gets 'tw' set to 72,
-  " 'cindent' is on in C files, etc.
-  " Also load indent files, to automatically do language-dependent indenting.
-  filetype plugin indent on
+" Enable file type detection.
+" Use the default filetype settings, so that mail gets 'tw' set to 72,
+" 'cindent' is on in C files, etc.
+" Also load indent files, to automatically do language-dependent indenting.
+filetype plugin indent on
 
-  " Put these in an autocmd group, so that we can delete them easily.
-  augroup vimrcEx
+" Put these in an autocmd group, so that we can delete them easily.
+augroup vimrcEx
   au!
 
   " For all text files set 'textwidth' to 78 characters.
@@ -65,13 +50,7 @@ if has("autocmd")
     \   exe "normal! g`\"" |
     \ endif
 
-  augroup END
-
-else
-
-  set autoindent               " always set autoindenting on
-
-endif " has("autocmd")
+augroup END
 
 " Convenient command to see the difference between the current buffer and the
 " file it was loaded from, thus the changes you made.
@@ -80,8 +59,3 @@ if !exists(":DiffOrig")
   command DiffOrig vert new | set bt=nofile | r ++edit # | 0d_ | diffthis
                  \ | wincmd p | diffthis
 endif
-
-" Prevent that the langmap option applies to characters that result from a
-" mapping.  If unset (default), this may break plugins (but it's backward
-" compatible).
-set langnoremap