bindings: remove the jumpy-scrolling toggle entirely

It is still possible to use --jumpyscrolling on the command line or
'set jumpyscrolling' in a nanorc file, but a user will have to restart
nano when they decide they want chunky instead of smooth scrolling,
a decision that should be rather rare.

This frees up the M-S keystroke to be reused for toggling softwrap.

doc/nano.texi

@@ -646,9 +646,6 @@ The following global toggles are available:
 @item Whitespace Display
 @kbd{Meta-P} toggles the displaying of whitespace (@pxref{Whitespace}).
 
-@item Scrolling
-@kbd{Meta-S} toggles the @option{-j} (@option{--jumpyscrolling}) command-line option.
-
 @item Expert/No Help
 @kbd{Meta-X} toggles the @option{-x} (@option{--nohelp}) command-line option.
 
@@ -1430,9 +1427,6 @@ Toggles the presence of the two-line list of key bindings at the bottom of the s
 @item constantshow
 Toggles the constant display of the current line, column, and character positions.
 
-@item smoothscroll
-Toggles smooth scrolling (when moving around with the arrow keys).
-
 @item softwrap
 Toggles the displaying of overlong lines on multiple screen lines.
 

doc/nanorc.5

@@ -771,9 +771,6 @@ Toggles the presence of the two-line list of key bindings at the bottom of the s
 .B constantshow
 Toggles the constant display of the current line, column, and character positions.
 .TP
-.B smoothscroll
-Toggles smooth scrolling (when moving around with the arrow keys).
-.TP
 .B softwrap
 Toggles the displaying of overlong lines on multiple screen lines.
 .TP

src/global.c

@@ -1256,7 +1256,6 @@ void shortcut_init(void)
 	/* Group of "Appearance" toggles. */
 	add_to_sclist(MMAIN, "M-X", 0, do_toggle_void, NO_HELP);
 	add_to_sclist(MMAIN, "M-C", 0, do_toggle_void, CONSTANT_SHOW);
-	add_to_sclist(MMAIN, "M-S", 0, do_toggle_void, JUMPY_SCROLLING);
 	add_to_sclist(MMAIN, "M-$", 0, do_toggle_void, SOFTWRAP);
 #ifdef ENABLE_LINENUMBERS
 	add_to_sclist(MMAIN, "M-#", 0, do_toggle_void, LINE_NUMBERS);
@@ -1411,8 +1410,6 @@ const char *flagtostr(int flag)
 			return N_("Help mode");
 		case CONSTANT_SHOW:
 			return N_("Constant cursor position display");
-		case JUMPY_SCROLLING:
-			return N_("Jumpy scrolling (per half-screen)");
 		case SOFTWRAP:
 			return N_("Soft wrapping of overlong lines");
 		case WHITESPACE_DISPLAY:
@@ -1664,8 +1661,6 @@ keystruct *strtosc(const char *input)
 			s->toggle = NO_HELP;
 		else if (!strcasecmp(input, "constantshow"))
 			s->toggle = CONSTANT_SHOW;
-		else if (!strcasecmp(input, "smoothscroll"))
-			s->toggle = JUMPY_SCROLLING;
 		else if (!strcasecmp(input, "softwrap"))
 			s->toggle = SOFTWRAP;
 #ifdef ENABLE_LINENUMBERS