Error if type of special function for attached class is not what it should be

[v0dro]

For example, the deallocate function for attached classes must not take in arguments and must be of return type void. Similar constraints exist for the others as well. These must be adhered to.

• deallocate function.
• allocate function.
• memcount function.
• get_struct function.

Also, if the user fails to write a deallocate function the compiler must raise an error and state so.