have a clear folders layout

As a new comer to this project I failed to find the logic behind the folders layout, which makes it harder to contribute.

If there is a logic - let's document it and publish it in README.
Else - I suggest finding a good standard layout, ie:
```
.
+-- [src]
+-- [test]
| +-- [unit]
| +-- [integration]
| +-- [scripts] (?)
+-- [libs] / [includes]
+-- [examples]
```

And reorder the project accordingly

Start by mapping the current repository folders and reviewing the README, then determine whether the existing layout has a consistent logic. Done means either documenting that layout in the README or agreeing on and applying a standard structure across the project.

Written by the indexing model from the issue text.