clear screen at exit using escape sequence

[pythonik]

[kristofer]

+1 on this one

[skx]

Good change, but perhaps more obvious to place the clear-screen in the at-exit handler?

[pythonik]

@skx agree

[Expector-Hutch]

Oh, we do the same thing. But maybe we can just use '\033c' to do the similar thing. Please look at this.