Remove old tests

Removed the old empty tests file.  I'll be adding Kiwi into the project later.
Implement a few linked list functions.

Various functions were implemented for the linked list including some removal,
addition and enumeration of object.

Added some 'TODO' flags to unimplemented methods.

Fast enumeration doesn't quite work perfectly yet.  It enumerates fine but
gives back CF c-style objects instead of the objective-c counterparts.

There is porbably due to toll free bridging in one direction but not the other.