Plotting subbasin from a given point of its discharge from 'routing.nc' ORCDHIEE file
  Each river is composed of different subbasins. Grouped up-flow. This function use a different color
  for the first level of suubbasins, and a different degree of color for the sub-subbasins of the first level
  It takes output from `subbasin' function from 'nc_var.py'

draw_subbasin(ncfile, values)
  ncfile= file to use produced with nc_var.py#subbasin function
  values= [subasiname]:[rangecolors]:[mapv]:[basinlinewidth]:[drawsubid]:[gtit]:[figkind]:[legvals]:[figurename]:
      [drawrivers]:[closefig]
    [subasiname]= name of the subbasin ('!' for spaces)
    [rcolor]= '@', list of 'r|g|b' 1-based colors (as much as first level sub-flow). 'None' for automatic
    [mapv]= map characteristics: [proj],[res]
      see full documentation: http://matplotlib.org/basemap/
      [proj]: projection
        * 'cyl', cilindric
        * 'lcc', lambert conformal
      [res]: resolution:
        * 'c', crude
        * 'l', low
        * 'i', intermediate
        * 'h', high
        * 'f', full
    [basinlinewidth]= with of the line to draw the basin
    [drawsubid]= wehther sub-flow ids should be plot or not
    [graphtit]= title of the graph ('|', for spaces)
    [legvals]=[locleg]|[fontsize]:
      [locleg]: location of the legend (0, autmoatic)
        1: 'upper right', 2: 'upper left', 3: 'lower left', 4: 'lower right',
        5: 'right', 6: 'center left', 7: 'center right', 8: 'lower center',
        9: 'upper center', 10: 'center'
      [fontsize]: font size for the legend (auto for 12)
    [figname]= name of the figure
    [drawrivers]= whether rivers from pythons' data-based have to be added or not
    [closefig]= whether figures should be closed or not