IGMPv3: fixes in processReport() method

- Group-and-Source-Specific Queries are not sent if the source list is empty
- Fix source list of queries sent in EXCLUDE(X,Y) -> TO_IN(A) -> ... transition
- Fix source list of queries sent in EXCLUDE(X,Y) -> TO_EX(A) -> ... transition
- deleted if statements with the same code in the two branches
IGMPv3: set operations expect sorted vectors
IGMPv3: fix unused vector in processQuery()
IGMPv3: refactored data access
IGMPv3: removed superfluous 'std::' prefixes
IGMPv3: cosmetics
IGMPv3: fix in Response processing

INCLUDE (A) -> TO_EX(B) -> ... transition used wrong A in Delete (A-B) action
IGMPTester: add '.' after dumped lines
IGMPv3: added test for checking leave latency