The Avro instance is now created inside a static class method. This brings
it in line with how other modules create instances.
Converted all strings to std::string and updated their usage.
By storing the table maps in a std::unordered_map, the storage of mapped
tables is made dynamic. This also makes the management of mapped tables a
lot more robust.
The HASHTABLE can be replaced with std::unordered_map. This simplifies the
management by making the deletion of old objects automatic.
More cleanup and refactoring is needed to make the contained classes
cleaner.
The avrorouter no longer uses the housekeeper for the conversion
task. This prevents the deadlock which could occur when clients were
notified at the same time that the binlogrouter was adding a master
reconnection task.
The instance and session objects are now C++ structs. The next pointers
for the sessions was removed as it is not the appropriate place to store
this information. This means that the client notification functionality is
broken in this commit.
