Cosmetic changes.  Rename varialbe name topology to linkDiscovery, and getTopology to getLinkDiscoveryManager in LinkDiscoveryManagerTest.java.

Update to link discovery manager.  LLDPs are sent every one second; with a three second timeout on ports where links were already found.  On ports where links are not present, LLDPs are sent once in every 15 seconds.

2 - Update module HA role change actions
3 - Add unit tests for HA role changes

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.

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

Clean-up of and javadoc to switch cluster computation code and corresponding
data structure.

Rewriting switch cluster computation to return strongly connected components in the presence of unidirectional links.  The notion of internal switchPort is also changed.