ENH: Evaluate can deal with LinearRegression object. Now required .fit() explicit calls.

LinearRegression schemes may not be able to do alpha CV, so have a function which can detect algorithms which can handle this.

Evaluate now required a .fit() call in order to make ECI's. It must therefore be called explicitly, rather than called implicitly.

This actually undoes some functionality which was introduced in 0.11.6, because I didn't realise how many other LinearRegression schemes were available, which weren't usable - tests to verify this won't happen again have been added.