Directory Loading

Added the ability to parse the directory and store it in a
Directory struct. This data has utility functions that can be used
to work with the directory to find any lump we could need. This
patch should fix up issue #3.

src/main.rs

@@ -9,10 +9,29 @@ fn main() {
 Header:
     Identifier: {}
     Lump Count: {}
-    Initial Offset: {}",
+    Initial Offset: {}
+    Number of Found Lumps: {}",
         wadutils::get_wad_path(&wad_file),
         wadutils::get_wad_type(&wad_file),
         wadutils::get_num_lumps(&wad_file),
-        wadutils::get_init_offset(&wad_file)
+        wadutils::get_init_offset(&wad_file),
+        wadutils::get_directory_len(&wad_file)
+    );
+
+    println!("First 15 Directory Entries:");
+
+    for i in 0..15 {
+        println!(
+            "\t{}\tName {}\tPosition {}\tSize {}",
+            i,
+            wadutils::get_lump_name(&wad_file, i),
+            wadutils::get_lump_offset(&wad_file, i),
+            wadutils::get_lump_size(&wad_file, i)
+        );
+    }
+
+    println!(
+        "Index of e1m1 is: {}",
+        wadutils::get_index_from_name(&wad_file, "e1m1").unwrap()
     );
 }