Tell comint to set TERM=emacs for fsi, and don't force using a pipe

We want to be able to use fsi's tab-completion, but we can't if we have
to pass --readline- as it turns off readline support. comint reports itself
as a dumb-terminal by default, which causes fsi to treat it like one. Setting
TERM=emacs (or likely and value that's not 'dumb') appears to let us interact
with fsi in the way we want to.

The previous combination of (process-connection-nil) and setting --readline- was
probably done to get around fsi's behavior when using a pty and TERM=dumb, but Im
not 100% sure of that.

This setup for init-ing the inferior fsharp process might need revisted in the future.

Author: jdodds

inf-fsharp-mode.el

@@ -90,7 +90,14 @@ be sent from another buffer in fsharp mode.
 	  (or cmd (read-from-minibuffer "fsharp toplevel to run: "
 					inferior-fsharp-program)))
     (let ((cmdlist (inferior-fsharp-args-to-list inferior-fsharp-program))
-          (process-connection-type nil))
+          ;; fsi (correctly) disables any sort of console interaction if it
+          ;; thinks we're a dumb terminal, and `comint-term-environment'
+          ;; (correctly) defaults to setting TERM=dumb on systems using
+          ;; terminfo, which is basically every modern system.
+          ;;
+          ;; we want to make use of fsi's tab completion, so tell comint
+          ;; to set TERM=emacs for our inferior fsharp process.
+          (comint-terminfo-terminal "emacs"))
       (with-current-buffer (apply (function make-comint)
                                   inferior-fsharp-buffer-subname
                                   (car cmdlist) nil