Fortran 2003 OOP linked list.

Code in this disscussion: https://software.intel.com/en-us/forums/intel-visual-fortran-compiler-for-windows/topic/518263

Tested compilers:

1. gfortran 4.8.4 (failed, gfortran has problem with the allocatable attribute for character).
2. Intel Fortran 2018 Composer Edition for Linux (passed). This shows that Intel Fortran has better implementation of OOP features of Fortran 2003 standard.