Add DCA script

[Dessoul]

A script that pass configured market order when called, used in DCA strategy

[veox]

Providing an example configuration file (with keypath/pair/type/volume, not keyfile) would be highly desirable.

[veox]

This is a rather convoluted way of reading in configuration. :)

If there's a file with python syntax, e.g. DCABot.config.py, it can be imported and used directly. E.g., like this.

[veox]

If you don't have time to work on it now, I could revisit it later myself.

[Dessoul]

Hi. I made the configuration file example, but I did not succeed to add this in this pull request.
Anyway this is somewhere in this repo. Sorry for the mess.
Really interesting your example, I will remind this. To be honest I never used Python before this :)
But I am not sure how to use it with multiple instances of the same variables, so I think it will be more efficient if you have a look by yourself.
Once again, thank you for the work you did here.

[veox]

I'm closing this PR for now, since I don't have the time to re-work it to be straightforward ATM.

Issue #30 links here for tracking purposes.