Automatic -a parameter; option to skip memory check; output improvement

wGRR

@@ -37,7 +37,7 @@ display_usage() {
 	echo "                        recommended: at least 4"
 	echo "                        Note: if wGRR is run on Maestro via sbatch, this number only applies to the"
 	echo "                           MMseqs step"
-	echo "   -a <integer>      Number of genomes comparisons to be performed in each thread."
+	echo "   -a <auto/integer>    Number of genomes comparisons to be performed in each thread."
 	echo "                        Increasing this will decrease the number of tasks to be performed"
 	echo "                           but each task will take longer and use more RAM."
 	echo "                        default: auto"