Javadoc
This class is the central dispatch point for Java 6 annotation processing.
This is created and configured by the JDT core; specifics depend on how
compilation is being performed, ie from the command line, via the Tool
interface, or within the IDE. This class manages the discovery of annotation
processors and other information spanning multiple rounds of processing;
context that is valid only within a single round is managed by
RoundDispatcher. There may be multiple instances of this class;
there is in general one of these for every Compiler that has annotation
processing enabled. Within the IDE there will typically be one for every
Java project, because each project potentially has a separate processor path.
TODO: do something useful with _supportedOptions and _supportedAnnotationTypes.