Update gga4r to standard gem file format

Hey,

This is a big pull request, I moved a lot of the files to the "standard" layout for gems and cleaned up some unneeded files.

Also, I made some changes to the genetic algorithm itself, instead of storing successive generations, it stores a total population.  Then, before it mutates or combines, it copies the current population, does the mutation/combination and then adds it to the current population.

Doing it this way yields faster mutation, but the population grows rapidly (doubling after each evolution), so it is a good idea to limit the maximum population.

Thanks