GammaLib

We should review the interfaces of all classes to make sure that all interfaces are homogeneous and also complete. This is an important step towards the first stable release which will enter under interface control.

Here a couple of principles that should be respected during interface review:

• Each class should have a constructor that allows one-line construction of a meaningful objects.
  This makes programming much easier, and prevents the need for a two step process for object creation (allocation and setting). The object constructor should take the most relevant parameters as arguments. Specific attributes can always be set using additional methods.

• If a class has an assignment method that assigns n elements of a given type (such as the std::vector.assign() method), the first argument is the number of elements n, followed by the element.