prints tree to visualise

[amishas157]

Resolves #7

An example following:

[daniel-j-h]

Awesome, this is beautiful! If you save SVGs you can handle larger trees and zoom in or out 🚀

(There are some issues with Travis, I think you need to adapt your code to latest master a bit)

[daniel-j-h]

Ah, what comes to mind: in the plot we see how you store strings in their original form.

What we probably want to do is compute the metric on normalized strings and user query, so that e.g. case-sensitivity doesn't matter, the strings are in unicode normal form, maybe even handling digits and words the same (think: 2nd street, second street), country-specific abbreviations, and language-specifics.

Just some food for thought, we don't have to implement all of those :)