Added more specific declarations to some node-related functions in
pake.grass API definition file
Tokenizer now supports quote-escaping inside strings and
enforces the fact that strings must not be broken by newlines
Strings ca span multiple lines using concatenation
Fixed bugs in dequoting and string concatenation, implemented typeof for string (not exposed in Grass, however), basic type checking in function call verification
Fixed anothe rbug in pre-translation string concatenation