Reorganize some of the unwieldly parts of the codebase

* Moved commands into their own folder to reduce `bin.rs`'s size
* Moved all of the VFS-related functionality into its own folder
* Documented a lot of functions, including a few very obscure ones

src/core.rs

@@ -1,8 +1 @@
-#[derive(Debug, Clone)]
-pub struct Config {
-    pub port: u64,
-    pub verbose: bool,
-    pub server_id: u64,
-}
-
 pub type Route = Vec<String>;