starting transition to éCO2mix v2 file format

* new url to download daily data file
Merge branch 'v2fileformat'
migration to v2 daily file format

analysis shows that:
* v2 daily files have a uniform header line (good)
* BUT data columns are filled with '' or 'ND' when not available
* and consumption data are not available prior to 2010-11-16 (very bad)

Therefore, daily data files from 2000 to 2010-11-15 are kept 'as is' for now.