Use in tty mode

[proux01]

To be able to use PG with emacs -nw, I need to add the following line to my .emacs

(setq overlay-arrow-string nil)

otherwise a useless arrow => hides the first two characters of the current line.

Another small annoyance comes from the - sign displayed in front of each hypothesis in the goals` buffer. I guess it is meant to fold the corresponding hypothesis but I couldn't get it to work (neither RET not TAB do fold anything). Fortunately enough nothing is displayed in the first two columns of that buffer so this doesn't hide anything (it still tends to make the cursor less visible when over it though). Note that magit seems to have a folding mechanism that works perfectly, even in tty mode, but I didn't look at how it is implemented.