#2 Add -m option.

[Anonymous]

Per discussion in http://sourceforge.net/mailarchive/forum.php?thread_name=CAGX8AEnXojDL2ZqOT63_fOngz02WqRRdzpEJWVqfxGuptby18Q%40mail.gmail.com&forum_name=varianttools-devel , we should allow users to specify a message for each variant table.

[Bo Peng]

I am not sure if we need to do this because none of the other applications (e.g. helixtree) does this.