Annotators should be initialized in the same thread that their process method will later be called on

It is more convenient if an annotator is initialized on the same thread that it is later called on. Some components may use thread-local data and they won't work in UIMA-AS currently. Another advantage of doing the initialization in the processing thread is that you could initialize multiple instances of the annotator in parallel instead of sequentially, which may be faster for a multi-core machine.