Constant Access Getter Functions

Class member functions that do not modify the class instance should be defined to indicate this, which is coded as a trailing const on the function inside the class definition:

class MyClass {
    int value;
    ...
public:
    int value(void) const
    {
        return m_value;
    }
    int valueSquared(void) const;
}

If the function body is defined in class source file instead in the class definition in the header file, the trailing const is also necessary:

int MyClass::valueSquared(void) const
{
    return m_value * m_value;
}

The functions in the Table, Token and Translator classes that don't modify the instances were made constant functions.  The Parser class doesn't have any non-modifying access functions.  The getToken() function was also renamed to the more consistent token().  This is a good place to create another development tag: v0.2-4.

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