Perf: Index codeobjects objects by fullname

Before

  $ time bin/inch ../rails/activerecord/
  real  1m19.090s
  user  1m18.959s
  sys 0m0.166s

After

  $ time bin/inch ../rails/activerecord/
  real  0m56.371s
  user  0m56.274s
  sys 0m0.122s
Prefer `public_send(name)` over `method(name).call`

Before

  $ time bin/inch ../rails/activerecord/
  real  0m56.371s
  user  0m56.274s
  sys 0m0.122s

After

  $ time bin/inch ../rails/activerecord/
  real  0m55.688s
  user  0m55.540s
  sys 0m0.170s
Prefer `Module#const_get(class_name)` over `eval(class_name)`

Before

  $ time bin/inch ../rails/activerecord/
  real  0m55.688s
  user  0m55.540s
  sys 0m0.170s

After

  $ time bin/inch ../rails/activerecord/
  real  0m54.399s
  user  0m54.289s
  sys 0m0.134s
Merge pull request #5 from splattael/perf

Performance optimizations