bindings: make ^T invoke the "Execute Command" menu, and ^T^T the Speller

Make the "Execute Command" menu accessible also with a single keystroke
(^T), not just with a double one (^R^X).  This is useful, because no one
will suspect that "Execute Command" can be found behind "Read File".

To not disturb muscle memory too much for people who are used to ^T
invoking the Spell Checker, a second ^T will invoke it.

src/files.c

@@ -1072,7 +1072,7 @@ bool execute_command(const char *command)
 
 /* Insert a file into the current buffer, or into a new buffer when
  * the MULTIBUFFER flag is set. */
-void do_insertfile(void)
+void do_insertfile(bool execute)
 {
 	int response;
 	const char *msg;
@@ -1080,7 +1080,6 @@ void do_insertfile(void)
 		/* The last answer the user typed at the status-bar prompt. */
 #ifndef NANO_TINY
 	format_type was_fmt = openfile->fmt;
-	bool execute = FALSE;
 #endif
 
 	/* Display newlines in filenames as ^J. */
@@ -1269,9 +1268,18 @@ void do_insertfile(void)
 void do_insertfile_void(void)
 {
 	if (!in_restricted_mode())
-		do_insertfile();
+		do_insertfile(FALSE);
 }
 
+#ifndef NANO_TINY
+/* If the current mode of operation allows it, go prompt for a command. */
+void do_execute(void)
+{
+	if (!in_restricted_mode())
+		do_insertfile(TRUE);
+}
+#endif
+
 /* For the given bare path (or path plus filename), return the canonical,
  * absolute path (plus filename) when the path exists, and NULL when not. */
 char *get_full_path(const char *origpath)

src/global.c

@@ -693,7 +693,7 @@ void shortcut_init(void)
 	const char *append_gist = N_("Toggle appending");
 	const char *prepend_gist = N_("Toggle prepending");
 	const char *backup_gist = N_("Toggle backing up of the original file");
-	const char *execute_gist = N_("Execute external command");
+	const char *execute_gist = N_("Execute a function or an external command");
 	const char *pipe_gist =
 		N_("Pipe the current buffer (or marked region) to the command");
 	const char *convert_gist = N_("Do not convert from DOS/Mac format");
@@ -793,13 +793,13 @@ void shortcut_init(void)
 		N_("Paste"), WITHORSANS(paste_gist), BLANKAFTER, NOVIEW);
 
 	if (!ISSET(RESTRICTED)) {
+#ifndef NANO_TINY
+		add_to_funcs(do_execute, MMAIN,
+				N_("Execute"), WITHORSANS(execute_gist), TOGETHER, NOVIEW);
+#endif
 #ifdef ENABLE_JUSTIFY
 		add_to_funcs(do_justify_void, MMAIN,
-				N_("Justify"), WITHORSANS(justify_gist), TOGETHER, NOVIEW);
+				N_("Justify"), WITHORSANS(justify_gist), BLANKAFTER, NOVIEW);
-#endif
-#ifdef ENABLE_SPELLER
-		add_to_funcs(do_spell, MMAIN,
-				N_("Spelling"), WITHORSANS(spell_gist), BLANKAFTER, NOVIEW);
 #endif
 	}
 
@@ -1035,8 +1035,12 @@ void shortcut_init(void)
 	add_to_funcs(zap_text, MMAIN,
 		N_("Zap"), WITHORSANS(zap_gist), BLANKAFTER, NOVIEW);
 
-#ifdef ENABLE_COLOR
 	if (!ISSET(RESTRICTED)) {
+#ifdef ENABLE_SPELLER
+		add_to_funcs(do_spell, MMAIN,
+				N_("Spell Check"), WITHORSANS(spell_gist), TOGETHER, NOVIEW);
+#endif
+#ifdef ENABLE_COLOR
 		add_to_funcs(do_linter, MMAIN,
 				N_("Linter"), WITHORSANS(lint_gist), TOGETHER, NOVIEW);
 		add_to_funcs(do_formatter, MMAIN,
@@ -1174,12 +1178,15 @@ void shortcut_init(void)
 	add_to_sclist(MMAIN, "M-R", 0, do_replace, 0);
 	add_to_sclist(MMOST, "^K", 0, cut_text, 0);
 	add_to_sclist(MMOST, "^U", 0, paste_text, 0);
+#ifndef NANO_TINY
+	add_to_sclist(MMAIN, "^T", 0, do_execute, 0);
+#endif
 #ifdef ENABLE_JUSTIFY
 	add_to_sclist(MMAIN, "^J", '\n', do_justify_void, 0);
 #endif
 #ifdef ENABLE_SPELLER
-	add_to_sclist(MMAIN, "^T", 0, do_spell, 0);
 	add_to_sclist(MEXECUTE, "^S", 0, do_spell, 0);
+	add_to_sclist(MEXECUTE, "^T", 0, do_spell, 0);
 #endif
 #ifdef ENABLE_COLOR
 	add_to_sclist(MMAIN, "M-B", 0, do_linter, 0);

src/proto.h

@@ -294,6 +294,9 @@ void read_file(FILE *f, int fd, const char *filename, bool undoable);
 int open_file(const char *filename, bool newfie, FILE **f);
 char *get_next_filename(const char *name, const char *suffix);
 void do_insertfile_void(void);
+#ifndef NANO_TINY
+void do_execute(void);
+#endif
 char *get_full_path(const char *origpath);
 char *safe_tempfile(FILE **f);
 #ifdef ENABLE_OPERATINGDIR