Add support for reading the file info format

I revisited this format, and discovered a lot of stuff I did wrong the
first time around when writing libxiv. Now that's fixed!

src/fiin.rs

@@ -0,0 +1,39 @@
+use std::ffi::CString;
+use std::io::Cursor;
+use binrw::binread;
+use crate::gamedata::MemoryBuffer;
+use binrw::BinRead;
+
+#[binread]
+#[br(magic = b"FileInfo")]
+#[derive(Debug)]
+pub struct FileInfo {
+    #[br(pad_before = 20)]
+    #[br(temp)]
+    entries_size : i32,
+
+    #[br(pad_before = 992)]
+    #[br(count = entries_size / 96)]
+    entries : Vec<FIINEntry>
+}
+
+#[binread]
+#[derive(Debug)]
+pub struct FIINEntry {
+    file_size : i32,
+
+    #[br(pad_before = 4)]
+    #[br(count = 64)]
+    #[br(map = | x: Vec < u8 > | String::from_utf8(x).unwrap())]
+    file_name: String,
+
+    #[br(count = 24)]
+    sha1 : Vec<u8>
+}
+
+impl FileInfo {
+    pub fn from_existing(buffer : &MemoryBuffer) -> Option<FileInfo> {
+        let mut cursor = Cursor::new(buffer);
+        Some(FileInfo::read(&mut cursor).ok()?)
+    }
+}

src/lib.rs

@@ -52,4 +52,7 @@ pub mod exh;
 pub mod exd;
 
 // Reading Havok XML sidecar files.
-pub mod skeleton;
+pub mod skeleton;
+
+// Reading file into files (FIIN).
+pub mod fiin;