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/rbx.rs

@@ -1,5 +1,6 @@
 use std::collections::HashMap;
 
+/// Represents data about a Roblox instance
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct RbxInstance {
@@ -9,10 +10,14 @@ pub struct RbxInstance {
     pub properties: HashMap<String, RbxValue>,
 }
 
+/// Any kind value that can be used by Roblox
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase", tag = "type")]
 pub enum RbxValue {
     String {
         value: String,
     },
+
+    // TODO: Other primitives
+    // TODO: Compound types like Vector3
 }