Cleanup misc.

Regarding debugger.txt (which was Spotted by @Hettomei):
The third section was empty, and the second section is very outdated.
Nvim doesn't have things like Balloon Evalutation and Sun Visual
workshop integration, so just remove the section.

Regarding everything else:
- term.[ch] and term_defs.h don't exist anymore, so remove refs to them
- Add ttybuiltin to vim_diff.txt. It should have been done before, but
  vim_diff.txt didn't exist when ttybuiltin was removed (done in
  3baba1e7bc6698e6bc9f1d37fce88b30d6274bc9,)

Helped-by: Justin M. Keyes <justinkz@gmail.com>

runtime/doc/debugger.txt

@@ -7,8 +7,6 @@
 Debugger Support Features				*debugger-support*
 
 1. Debugger Features		|debugger-features|
-2. Vim Compile Options		|debugger-compilation|
-3. Integrated Debuggers		|debugger-integration|
 
 ==============================================================================
 1. Debugger Features					*debugger-features*
@@ -106,29 +104,4 @@ Another way to use the balloon is with the 'balloonexpr' option.  This is
 completely user definable.
 
 ==============================================================================
-2. Vim Compile Options					*debugger-compilation*
-
-The debugger features were added explicitly for use with Sun's Visual
-WorkShop Integrated Programming Environment (ipe).  However, they were done
-in as generic a manner as possible so that integration with other debuggers
-could also use some or all of the tools used with Sun's ipe.
-
-The following compile time preprocessor variables control the features:
-
-    Alternate Command Input			ALT_X_INPUT
-    Debug Glyphs				FEAT_SIGNS
-    Debug Highlights				FEAT_SIGNS
-    Message Footer				FEAT_FOOTER
-    Balloon Evaluation				FEAT_BEVAL
-
-The first integration with a full IPE/IDE was with Sun Visual WorkShop.  To
-compile a gvim which interfaces with VWS set the following flag, which sets
-all the above flags:
-
-    Sun Visual WorkShop				FEAT_SUN_WORKSHOP
-
-==============================================================================
-3. Integrated Debuggers					*debugger-integration*
-
-
  vim:tw=78:sw=4:ts=8:ft=help:norl:

runtime/doc/options.txt

@@ -6771,7 +6771,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	by user preferences or the current theme is used.
 
 			     *'ttybuiltin'* *'tbi'* *'nottybuiltin'* *'notbi'*
-'ttybuiltin' 'tbi'	Removed. {Nvim}
+'ttybuiltin' 'tbi'	Removed. |vim-differences| {Nvim}
 
 				     *'ttyfast'* *'tf'* *'nottyfast'* *'notf'*
 'ttyfast' 'tf'		Removed. |vim-differences| {Nvim}

runtime/doc/various.txt

@@ -231,7 +231,7 @@ g8			Print the hex values of the bytes used in the
 			and |nvim-terminal-emulator| for more information.
 
 							*:!cmd* *:!* *E34*
-:!{cmd}			Execute {cmd} with the shell. See also 'shell'.
+:!{cmd}			Execute {cmd} with 'shell'. See also |:terminal|.
 
 			Any '!' in {cmd} is replaced with the previous
 			external command (see also 'cpoptions').  But not when

runtime/doc/vim_diff.txt

@@ -115,11 +115,12 @@ MS-DOS support:
 
 Other options:
   'macatsui'
-  'shortname'
   'shelltype'
+  'shortname'
   'termencoding'
   'textauto'
   'textmode'
+  'ttybuiltin'
 
 Other commands:
   :fixdel