Additional 'EvolutionResult' collectors

Add an additional result collector, which works nicely with the `Codec` interface:

``` java
EvolutionResult.toBestResult(Function<Genotype<G>, T> decoder);
```

Usage:

``` java
final ISeq<Point> route =
    Engine.builder(problem)
        .optimize(Optimize.MINIMUM).build()
        .stream()
        .limit(100)
        .collect(EvolutionResult.toBestResult(codec.decoder()));
```
