Added directfs

Added a very rudimentary file I/O system suitable for experimenting
with the language further. A better one will be designed when we have
sensible error management.

src/systems/directfs/mod.rs

@@ -1,2 +1,5 @@
-
+//! A rudimentary system exposing methods for Orchid to interact with the file
+//! system. All paths are strings.
 mod commands;
+
+pub use commands::DirectFS;