Performance

[tmck-code]

This PR provides a ~20% increase by optimising a few areas

• random selection of pokemon
• argument parsing
• redundant variable assignments

Some timings

• master: time fortune | ./pokemonsay

  real    0m0.044s
  user    0m0.025s
  sys     0m0.021s

• PR: time fortune | ./pokemonsay

  real    0m0.036s
  user    0m0.021s
  sys     0m0.017s

• Vanilla cowsay: time fortune | cowsay -f cows/Pikachu.cow

  real    0m0.032s
  user    0m0.019s
  sys     0m0.017s

[tmck-code]

I always click the wrong button! I'd meant this PR to be based off my master fork rather than this one 😄