Added options to suppress display of warnings and some other non-critical messages.

Handling of command line messages has been altered. The table of SNPs used in the prediction model should now
be passed with the parameter -t. The file with population data for genotype completion should now be
passed using the parameter -p. The flag -nw will suppress warning messages. The flag -q will quiet all
output messages that are informative but not strictly necessary for the program to function.