Deep merge should continue on Ptr, fixes #23

[dionysius]

Test case for #23. As stated there, the deep merge stops once a target is a pointer. The pointer should be dereferenced and the deep merge should continue.

[dionysius]

So, I can propose a fix for #23. This fix has a breaking change on the deep merge after the pointer! Before this fix, the deep merge stopped at this level where the pointer was. But I am sure this is the way it is supposed to work.