Implement Costs relative to net premium and fixed costs (no basis); Args to...

Implement Costs relative to net premium and fixed costs (no basis); Args to initializeCosts to quickly define the most common cost types

-) Costs with basis "NetPremium"
-) Costs with basis "Constant"
-) TODO: include them into the calculation of the Zillmer premium
-) Arguments to initializeCosts to quickly set the most common cost types.

Fixes #46, #40