Establish global module structure and/or API

[davidovitch]

A general package for common wind energy engineering analysis is proposed. This within the initial framework of DTU Wind Energy, but the goal is to make an open and institute agnostic python module. Due to the large number of codes, types of analysis, and the many involved different institutes, one monolithic package might not be the most practical (from a developers perspective) approach. Instead, we'll try to layout a base package.

How to handle extensions: as plugins (à la OpenMDAO) or as independent packages with a dependency on the base package (pip understand dependencies, you can even create a wheeler bundle that includes compiled dependencies, see docs)?

Since many things are still unknown at this stage, I think we should accept that during, say the first year, we will have code moving in and out of the base package and into the plugins/external packages all the time. Only after this initial time we should set a more rigid structure.

Regarding the name (of the base package that is), the only other candidate for a short version I could think of is WENG (wind energy engineering) or (py)weng(py), instead of WETB [pronounce as weeteebee].

Mads initial proposal is this specified with this commit: 6797fcc (or view the file).

Or after some modifications from David: f0d2244