Fix HandleNpcEvent packet structure

https://docs.google.com/spreadsheet/ccc?key=0AhhWNe1w3eWsdG5kRG54NUtCX0NCSVJOV3Y5dlFLTGc#gid=15
http://puu.sh/crjDd/1355cbfa68.png
Merge pull request #5 from Enerdy/patch-1