importation of a csv excel file
impexc2bd(filein,sep,fileout,arg1,...,argn)
* filein = name of the file to be imported (between quotes)
* sep = separator used in the filein (between quotes)
* fileout = name of the scilab file where to save the imported data (between quotes)
* argi = optional arguments
- 'namedat=xxx' where xxx is the name given to the field dates in the .csv file (default: dates)
- 'namena=x1;x2;...xn' where xi are the values that the Non Available data can take in the .csv file ('default: ' ' and '#N/A')
- 'prefix=xxx' where xxx is the prefix that will be added to the names of the variables in the .csv database to obtain their names in the Scilab .dat database
* Nothing: the imported series are saved in the file named fileout