Add default types for binary encoding, value encoding and permutation encoding

[haraldmaida]

Without knowing anything about the encoding of gene it is impossible to provide default implementations for crossover and mutation operator. Therefore it would make sense to implement the basic types of gene encodings, which are:

• binary encoding
• value encoding
• permutation encoding
• tree encoding

the implementation will be split up into 2 parts. with this feature request only the first 3 encoding types:

• binary encoding
• value encoding
• permutation encoding

will be implemented. For tree encoding a separate issue will be created.

[haraldmaida]

I have defined traits for the encoding types, but they are not used until now. During implementation of the crossover and mutation operators I found that the implementations can be for basic data types and do not need to now about encoding schemes explicitly.

So the traits defining the encoding types are currently not used and if there is no purpose in having them I will remove them at some point.