Fixed empty strings in MabiDictionary

... not being parsed.
Fixed potential null ref in AI
Added OnCreation to item data

Doesn't do anything yet.
Fixed shops being loaded after NPCs

If they're loaded after the NPCs we can't create derived shops in the
NPC files.
Follow up 74527144f80c1619a0414e45fa4bd59241e5aee0

* Now actually using OnCreation.
* Now adding some book meta data from OnCreation.
Fixed null ref in MagicSeal
Added removing of keywords

* Added Remove(string) method
* Added client update (not based on actual research)
Added magic words script support

Magic word scripts are simple "function" calls inside item meta data,
found in sealed books, used to do things like training skills when
reading the books.