Implement copy constructor to prevent malloc errors

[jamesmulcahy]

Fixes #1

[Loki-Astari]

This is unsafe. You should not be managing raw pointers in your class.
If you use std::unique_ptr it will solve this problem.
As it stands this class is broken because it does not implement the rule of three/five (ie there is no assignment operator). So you still have potential malloc errors (though I hope there are no mallocs in your code)