Module for unspecified behavior routine

Introduces a new module unspec.c with two helper routines called unspec() and chkptr() as well as a new header command.h that provides the interface for those two helpers. The unspec() routine is the unspecified behavior routine mentioned in the issue #3. The chkptr() routine is similar to unspec(), but is meant to handle out-of-memory situation when indicated by *alloc() and strdup() system interfaces.