Add equals/hash methods for serializable classes

Corresponding classes are:

UC2: JointRecordParents, SensorParentKey

UC4: HourOfDayKey

added In Progress modul/benchmarks labels

changed the description

created merge request !27 (merged) to address this issue

mentioned in merge request !27 (merged)

closed via merge request !27 (merged)

mentioned in commit 6a3ecbe5

mentioned in merge request !29 (merged)