Design and implement class invariants/interfaces for base types in ClusterHitFinder algorithm

All base class types should be test-driven.
The classes specific for given implementation should inherit from them.

Example:

1. BaseTpc2dCluster: public TObject
2. Tpc2dClusterImplementation_1: public BaseTpc2dCluster
3. Tpc2dClusterImplementation_2: public BaseTpc2dCluster

Base class type must contain only information which is required for universal testing of all algorithm implementations.