flatzinc version 0.2.2

• reexport error types from nom:

VerboseError
ParseError
convert_error
IResult
Err

• add parsing function for flatzinc statements:

pub enum FzStmt {
    Predicate(PredicateItem),
    Parameter(ParDeclItem),
    Variable(VarDeclItem),
    Constraint(ConstraintItem),
    SolveItem(SolveItem),
}
pub fn fz_statement<'a, E: ParseError<&'a str>>(input: &'a str) -> IResult<&'a str, FzStmt, E> {
...
}