Improve coding style

[cbrnr]

Fixes #79. @mbillingr can you confirm if it is OK to move the cat_trials import outside of the function?

[mbillingr]

Yes, that is OK. In fact, you could also move the dot_special import outside.

In principle, we could move all local imports and the scipy import outside. The local imports are available anyway, and scipy is a obligatory dependency of scot. Only sklearn is optional and should remain inside the function.

[cbrnr]

@mbillingr I've changed the input argument order in some functions. Could you please check if this is OK, or are we unnecessarily breaking the API? I thought the new order makes more sense.

[cbrnr]

I think I'm going to revert the changed argument order. The statistics example produces different results.

[mbillingr]

The problem with changing the argument order is that you will never know for sure if you found all the places where the function is used.

[cbrnr]

Agreed. That's why I reverted it.

[mbillingr]

@cle1109 can you rebase this branch to the current master?

[cbrnr]

@mbillingr could you please check if the changes are OK? If yes, please merge it - I want to avoid blowing up this PR more, because this means a lot of manual merging when rebasing. We can continue to improve the code style in another PR.