rcfile: add bindable function 'execute', for access to "Execute Command"

(This should have been added three weeks ago when ^T was rebound.)

doc/nano.texi

@@ -1284,6 +1284,10 @@ Shows the current cursor position: the line, column, and character positions.
 @item wordcount
 Counts the number of words, lines and characters in the current buffer.
 
+@item execute
+Prompts for a program to execute.  The program's output will be inserted
+into the current buffer (or into a new buffer when @kbd{M-F} is toggled).
+
 @item speller
 Invokes a spell-checking program, either the default @command{hunspell}
 or GNU @command{spell}, or the one defined by @option{--speller} or

doc/nanorc.5

@@ -599,6 +599,10 @@ Shows the current cursor position: the line, column, and character positions.
 .B wordcount
 Counts the number of words, lines and characters in the current buffer.
 .TP
+.B execute
+Prompts for a program to execute.  The program's output will be inserted
+into the current buffer (or into a new buffer when \fBM-F\fR is toggled).
+.TP
 .B speller
 Invokes a spell-checking program, either the default \fBhunspell\fR or GNU
 \fBspell\fR, or the one defined by \fB\-\-speller\fR or \fBset speller\fR.

src/rcfile.c

@@ -256,6 +256,8 @@ keystruct *strtosc(const char *input)
 	else if (!strcmp(input, "paste"))
 		s->func = paste_text;
 #ifndef NANO_TINY
+	else if (!strcmp(input, "execute"))
+		s->func = do_execute;
 	else if (!strcmp(input, "cutrestoffile"))
 		s->func = cut_till_eof;
 	else if (!strcmp(input, "copy"))