added vim-like count feature for certain commands

[dohsimpson]

see issue #140 supported commands: run to cursor; movements(j/k/h/l); stack movements(u/d) Bug: UI is not correctly updated if program terminated after count command

[asmeurer]

Is it possible to make it work with arrow keys too?

[asmeurer]

Should we add some kind of indicator to the UI so the user can see what number they've typed?

[asmeurer]

Seems like s and n should be supported as well.

[dohsimpson]

The count function is only registered in the listener of DebuggerUI.source_sigwrap, which doesn't have control of "Up" and "Down". But I think it's doable if we register it as a top level listener.

I agree that UI indicator would be great. But I'm not very familiar with pudb's UI codebase, so I would need some help on that.

Unfortunately s and n does not use Breakpoint and thus there's no API for adding ignore count.