Hard to tell when it will finish

[kenogo]

• Pycorrelate version: 0.3
• Python version: 3.6.4
• Operating System: Windows

Description

Correlation tends to be a time-consuming task, and it would be nice to have some kind of progress bar to get an estimate for how long it's going to take. This should be rather easy to implement, as we know the length of the arrays. I suggest adding it as a optional parameter to the functions, like

pcorrelate(..., progress=False)

This way, users don't get unexpected output in their terminal, but they can enable this useful feature if they want to. I'm willing to work on this.