Feature/refactor

Added docs and renamed variables for clarity. Modules now make use of RenderResult. Changes to the player allow for multiple renderers and export options. The config file now requires a list of Renderers and a list of exporters rather than just a list of handlers.
The naming for `type` is somewhat ambiguous.  I think it would be better if (as @asmacdo and I just discussed) this were named `handler_type` or something of that sort.  Just so it's a little more descriptive.