Symbol = function (name, type, address, byReference) {
        this.name = name;
        this.type = type;
        this.address = address;
        this.isNative = false;
        this.value = null;
        this.byReference = byReference;
    }
Create a new symbol.

name: name of symbol (original case is fine).
type: type of the symbol (Node.SIMPLE_TYPE, etc.).
address:
    if variable: address of symbol relative to mark pointer.
    if user procedure: address in istore.
    if system procedure: index into native array.
isNative: true if it's a native subprogram.
value: node of value if it's a constant.
byReference: whether this symbol is a reference or a value. This only applies
    to function/procedure parameters.