Bug fixes to ChNodeFEAxyzD.
Bug fixes to ChNodeFEAxyzD.

- allocate memory for variables in copy constructor
- fix incorrect offsets in functions interfacing to variables (Note that these functions are currently not used)

projectchrono/chrono,projectchrono/chrono,dariomangoni/chrono,tjolsen/chrono,rserban/chrono,rserban/chrono,projectchrono/chrono,armanpazouki/chrono,Milad-Rakhsha/chrono,armanpazouki/chrono,Milad-Rakhsha/chrono,jcmadsen/chrono,dariomangoni/chrono,dariomangoni/chrono,amelmquist/chrono,dariomangoni/chrono,tjolsen/chrono,rserban/chrono,amelmquist/chrono,amelmquist/chrono,Milad-Rakhsha/chrono,Milad-Rakhsha/chrono,amelmquist/chrono,andrewseidl/chrono,projectchrono/chrono,jcmadsen/chrono,projectchrono/chrono,rserban/chrono,rserban/chrono,jcmadsen/chrono,dariomangoni/chrono,amelmquist/chrono,tjolsen/chrono,dariomangoni/chrono,andrewseidl/chrono,andrewseidl/chrono,jcmadsen/chrono,rserban/chrono,Milad-Rakhsha/chrono,rserban/chrono,Milad-Rakhsha/chrono,jcmadsen/chrono,armanpazouki/chrono,jcmadsen/chrono,andrewseidl/chrono,amelmquist/chrono,andrewseidl/chrono,jcmadsen/chrono,projectchrono/chrono,armanpazouki/chrono,armanpazouki/chrono,tjolsen/chrono,tjolsen/chrono,armanpazouki/chrono