Rename functions due to typo (keystoke -> keystroke)
Set isSymbol to 0 in SetChoiceInfo

SetChoiceInfo updates the ChoiceInfo for word or phrase, thus it needs to set
isSymbol to 0 to ensure it will not goto symbol choose in the following code.
See [1] for more information.

[1] http://code.google.com/p/chewing/issues/detail?id=472