Update indexWiki.c

Changed to new XML parsing algorithm. Moving from xmlTextReaderRead to xmlTextReaderNext cut off 12% of the time. Further re-structuring of the algorithm saved another 1-2%. It is more code, but it is less spaghetti, easier to read, and easier to tweak further.

55% of all time is parsing the XML.

see indexWiki_old_v1.c for previous revision