Redesign VFS around handles

libsystem/system.h

@@ -57,13 +57,13 @@ int exec (const char* path);
 int open (const char* path);
 
 /* Close a file */
-int close (const char* path);
+int close (int handle);
 
 /* Read a file */
-int read (const char* path, size_t off, uint8_t* buffer, size_t size);
+int read (int handle, size_t off, uint8_t* buffer, size_t size);
 
 /* describe a file */
-int describe (const char* path, struct desc* desc);
+int describe (int handle, struct desc* desc);
 
 /* send a message to a procgroup's mail */
 int mail_send (int pgid, void* mesg, size_t mesg_size);