help: pass subtopic into help() Now that we have multiple directories where help topics can live, we need a mechanism to access them. We already use "." to separate topic from section. So it seems logical to also use "." to denote the sub-directory of a topic. This patch teaches the help command to parse out the possible sub-topic and pass it to the help system.

help: add "internals" topic We introduce the "internals" help topic, which renders an index of available sub-topics. The sub-topics themselves are still not reachable via the help system.