New TopologyManager.  Previous TopologyImpl would simply do link discovery.  Cosmetic refactoring (renaming etc.) would be done separately.

Updates to BroadcastTree data structure; Renaming of IRoutingEngineService to IRoutingService; Updates to signatures of IRoutingService interface methods.

Introduce ILinkDiscovery as the base class from which ILinkDiscoveryService and ILinkDiscoveryListener are extended.  Introduce link types in ILinkDiscovery.  The link type is sent to all listeners.

switch. Added parameter to pushRoute to pass flow mod. command type and if
messages to be flushed after the write().

Add switchClusterBroadcastDomainMap to maintain the set of broadcast domains connected to each cluster. [#23198243]

Adding an id for broadcastdomain.

dispached on order. Changed default performance monitoring window to 1hr from 5min.
Fixed a bug in topology where routes were not getting recompured when an internal link
went down. (RoutingImpl.java around line 214).

Fixed JUnit tests.

Event-history for topology related events: switch connects/disconnects, links ups/downs, cluster merge/splits.

Conflicts:

	src/main/java/net/floodlightcontroller/util/TimedCache.java

2 - Added more comments to TopologyImpl.

2 - Added a call to change StaticFlowPusher push interval
3 - Added various comments

2 - Added a call to change StaticFlowPusher push interval
3 - Added various comments

Conflicts:

	src/main/java/net/floodlightcontroller/topology/internal/TopologyImpl.java