Embed trycf in guides as well / Use setup/preload code

[shaedrich]

According to trycf's docs code snippets can be embedded as you already did for docs. Could this be done for guides as well?

Additionally there is the possibility to add preload code which is not shown up in the editor (example). This could be used for some "test yourself" educating interactive guides.

With that preload code we could perhaps solve something else as well: There are some examples which could not be run because no other files exist or just a structure/an object or something like that have to be initialized before we can properly use a function. We could store the setup code needed elsewhere and load them for multiple examples as needed so we could also reuse it.