Merge: console: add simple progress bar that refreshes itself

Example:

~~~nit
import console

var pb = new TermProgress(10, 0)

for i in [1..10] do
	pb.update(i)
end
~~~

Will display something like:
~~~sh
20% [==========================>                                       ]
~~~

See documentation for more info about the progress bar.

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>

Pull-Request: #1859
Reviewed-by: Jean Privat <jean@pryen.org>