Added pose output reduction options

[atillack]

This PR adds the argument --output-cluster-poses which controls how many poses are output per result cluster.

The following options are available:

• 0 and all is the current default behavior which outputs all available poses
• a number greater than zero sets a fixed limit, i.e. --output-cluster-poses 2 would output the first two poses per result cluster
• auto uses the contact analysis and outputs poses which have additional Reactive and H-bonding interactions compared to the poses that came before them in the results cluster when sorted by energy - as such it should contain the largest amount of entropy of the results data but still could potentially reduce pose output significantly depending on a given system