Parse eigenclass declarations

Some useful links if you'd like to know more about this

https://stackoverflow.com/questions/2505067/class-self-idiom-in-ruby
http://viewsourcecode.org/why/hacking/seeingMetaclassesClearly.html
https://www.quora.com/What-does-this-code-mean-in-Ruby-a-class-String-self-end