Return LinkedHashMap (key:metakeyword, value:set of actual keywords
belonging to metakeyword) and assign key in the insertion order (cf)
LinkedHashMap.keySet() keeps the order)
input file format: metakeyword|keyword|keyword...
Annotator that removes cTAKES EntityMentions and Modifiers from the system view, and copies
over the manually annotated EntityMentions and Modifiers from the gold view.