Add character as a parameter in book method script functions

[Xandros]

Hi,

I'd like to suggest adding the character who is using the book as
a parameter in the book method script functions. Would be very
useful e.g. to make the result of IsWritable(...) dependant on the
char using the book. Also, in SetAuthor(..), SetTitle(..) and
SetLine(..) it would be useful to give the character some writing
animation or sound or other things.

Xandros