Remove `evaluate()` for partial derivatives

On The 2015 dev meeting we decided to switch to classic multi-index notation for evaluating partial derivatives. This was meanwhile implemented by adding the new method partial() doing exactly this.

I propose to remove the old method without deprecation. This is in line with our decision on the meeting. Originally we decided to make this a breaking change by switch the behaviour of evaluate(). The only difference would be, that we have a nicer name now.

This change would greatly simplify the implementation of the virtual interface. Currently the local basis interface supporting partial derivatives up to order 2 is an inheritance hierarchy of 6 levels just to implement old style evaluate().