Package structure

[alexcjohnson]

@eendebakpt Thanks for prodding me to do this - we would have had to sometime not too long anyway, to make qcodes pip-installable, but what I didn't know about is setup.py develop, which leaves the code where it is but links it to python the right way so the package is globally discoverable. so (cc @AdriaanRol ) no more monkeying with sys.path

Also notice that the test command is simplified now: you can do python setup.py nosetests because I put the coverage config into setup.cfg

However, I didn't solve your exact dependency issue @eendebakpt - because it seems to me matplotlib and pyqtgraph are both potentially tricky to install, so I left them as optional dependencies. They're still in setup.py as well as README.md but they won't be automatically upgraded.

[alexcjohnson]

Any comments before I merge this? Going once... going twice...

[AdriaanRol]

I didn't have time to test if it actually works but the code itself looks good 💃

[eendebakpt]

I didn't know about setup.py develop, but it works like a charm. Please merge!

I would like to add with-doctest=1 to setup.cfg, because I like doctest. Currently this conflicts with py35_syntax.py (I work with python 3.4), I have not figured out how to solve this.

[alexcjohnson]

Thanks @AdriaanRol
@eendebakpt great! I will look into with-doctest=1 as a separate PR