Added new methods getBoundThings and getBoundChannels to ItemChannelLinkRegistry.

Signed-off-by: Dennis Nobel <d.nobel@external.telekom.de>
Fixed notify of newly added and removed trackers inside ThingRegistry.

Signed-off-by: Dennis Nobel <d.nobel@external.telekom.de>
Merge branch 'integration-74' of https://github.com/qivicon/smarthome into integration-74