This submodule will handle saving the outfile to whatever format you
want.
For now, it can save in svg (default), png using inkscape, png, pdf or
ps using cairosvg.
Now :
- rootdir is the directory all the img paths will be relative to ;
defaults to '.'
- imgdir is the directory containing all required images ; defaults to
'res/ssbu'. It is expected to hold a 'chars' directory