Things to do:
URGENT
 - fix bug for null commands (not recognized actually)
 - add input line number to error messages
 - fix multilayer display of variations in column format (Ugly)

LATER
 - come up with a way to parse variations inside comments (for figurine pieces)
 - command line specification of chess symbols for a new language
 - to have configuration file
 - automatically add sufixes (.tex, ps, .asc, .roff .xboard.save ...) to
   output file
 - add a xboard save-position format
 - A ChessBase file output is being worked on

