Fix CSV_writer copy constructor:
Fix CSV_writer copy constructor:

- also copy the data (including formatting information) of the underlying output string stream.
- note that we do not copy the data buffer, as this would result in a shared buffer.

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