Remove 'guipty' references

Presumably due to tarruda's unifdefing, it was already a no-op at the
time of nvim's first commit.

It's probably better to be clear that it doesn't exist, as opposed to
users thinking `:set guipty` is doing something when it isn't.

runtime/doc/gui.txt

@@ -12,7 +12,6 @@ Vim's Graphical User Interface				*gui* *GUI*
 4. Making GUI Selections	|gui-selections|
 5. Menus			|menus|
 6. Extras			|gui-extras|
-7. Shell Commands		|gui-shell|
 
 Other GUI documentation:
 |gui_w32.txt|	For specific items of the Win32 GUI.
@@ -93,7 +92,7 @@ The personal initialization files are searched in the order specified above
 and only the first one that is found is read.
 
 There are a number of options which only have meaning in the GUI version of
-Vim.  These are 'guicursor', 'guifont', 'guipty' and 'guioptions'.  They are
+Vim.  These are 'guicursor', 'guifont', and 'guioptions'.  They are
 documented in |options.txt| with all the other options.
 
 Another way to set the colors for different occasions is with highlight
@@ -976,19 +975,4 @@ This section describes other features which are related to the GUI.
 A recommended Japanese font is MS Mincho.  You can find info here:
 http://www.lexikan.com/mincho.htm
 
-==============================================================================
-7. Shell Commands					*gui-shell*
-
-For the X11 GUI the external commands are executed inside the gvim window.
-See |gui-pty|.
-
-WARNING: Executing an external command from the X11 GUI will not always
-work.  "normal" commands like "ls", "grep" and "make" mostly work fine.
-Commands that require an intelligent terminal like "less" and "ispell" won't
-work.  Some may even hang and need to be killed from another terminal.  So be
-careful!
-
-For the Win32 GUI the external commands are executed in a separate window.
-See |gui-shell-win32|.
-
  vim:tw=78:sw=4:ts=8:ft=help:norl:

runtime/doc/options.txt

@@ -3361,11 +3361,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 
 
 						*'guipty'* *'noguipty'*
-'guipty'		boolean	(default on)
-			global
-			{only available when compiled with GUI enabled}
-	Only in the GUI: If on, an attempt is made to open a pseudo-tty for
-	I/O to/from shell commands.  See |gui-pty|.
+'guipty'		Removed. |vim-differences| {Nvim}
 
 						*'guitablabel'* *'gtl'*
 'guitablabel' 'gtl'	string	(default empty)

runtime/doc/quickref.txt

@@ -717,7 +717,6 @@ Short explanation of each option:		*option-list*
 'guifontwide'	  'gfw'     list of font names for double-wide characters
 'guiheadroom'	  'ghr'     GUI: pixels room for window decorations
 'guioptions'	  'go'	    GUI: Which components and options are used
-'guipty'		    GUI: try to use a pseudo-tty for ":!" commands
 'guitablabel'	  'gtl'     GUI: custom label for a tab page
 'guitabtooltip'   'gtt'     GUI: custom tooltip for a tab page
 'helpfile'	  'hf'	    full path name of the main help file

runtime/doc/usr_21.txt

@@ -77,13 +77,6 @@ better at it.  You can start a new shell this way: >
 This is similar to using CTRL-Z to suspend Vim.  The difference is that a new
 shell is started.
 
-When using the GUI the shell will be using the Vim window for its input and
-output.  Since Vim is not a terminal emulator, this will not work perfectly.
-If you have trouble, try toggling the 'guipty' option.  If this still doesn't
-work well enough, start a new terminal to run the shell in.  For example with:
->
-	:!xterm&
-
 ==============================================================================
 *21.3*	Remembering information; viminfo
 

runtime/doc/vim_diff.txt

@@ -132,6 +132,7 @@ MS-DOS support:
   'conskey'
 
 Other options:
+  'guipty'
   'macatsui'
   'shelltype'
   'shortname'

runtime/optwin.vim

@@ -592,8 +592,6 @@ if has("gui")
     call append("$", "guiheadroom\troom (in pixels) left above/below the window")
     call append("$", " \tset ghr=" . &ghr)
   endif
-  call append("$", "guipty\tuse a pseudo-tty for I/O to external commands")
-  call <SID>BinOptionG("guipty", &guipty)
   if has("browse")
     call append("$", "browsedir\t\"last\", \"buffer\" or \"current\": which directory used for the file browser")
     call <SID>OptionG("bsdir", &bsdir)

src/nvim/option.c

@@ -842,9 +842,6 @@ static vimoption_T
    (char_u *)NULL, PV_NONE,
    {(char_u *)NULL, (char_u *)0L}
    SCRIPTID_INIT},
-  {"guipty",      NULL,   P_BOOL|P_VI_DEF,
-   (char_u *)NULL, PV_NONE,
-   {(char_u *)TRUE, (char_u *)0L} SCRIPTID_INIT},
   {"guitablabel",  "gtl", P_STRING|P_VI_DEF|P_RWIN,
    (char_u *)NULL, PV_NONE,
    {(char_u *)NULL, (char_u *)0L}