Make a function taking path length as argument

[whit2333]

An ATOF Cluster knows nothing about path length and should not have it as a data member.

coatjava/reconstruction/alert/src/main/java/org/jlab/rec/atof/cluster/ATOFCluster.java

Lines 384 to 385 in b819ade

	public double getBeta() {
	//Need to change to non hardcoded value