Improve and test the EA for Feature Selection

[SebastianRehfeldt]

• test probs
• prob of mutation based on chromo size
• improvement_thresh
• smarter cross-over (test uniform?)
• smarter intialization
• smarter fitness function
  • use weights of features in classifier (maybe for mutation?)
  • replace classifier metric by distance metric
• increase diversity by eliminating duplicates
• ea without stats
• parallelize fitness assessment