In times past, Configuration and ConfigurationImpl, now renamed to BaseConfiguration and HtmlConfiguration, because a messy mixture of options, a place to access other shared data structures, and utility methods.

More recently, we have moved a lot of stuff out into separate abstractions, such as Messages, Resources, etc.

It would be good to do the same for options, by moving the code for shared options and HTML options out of the *Configuration classes into their own classes.

At the same time, it would be good to rename many of the fields used to store the value of options, to use a more standard camelCase convention.
And some of the comments need improving as well.