Vertex Loading

Added the ability to load vertex data from the WAD. Still needs
some processing to make more robust, but for now is loading data.

src/utils/helpers.rs

@@ -41,3 +41,11 @@ pub fn read_u32_le(bytes: &[u8]) -> u32 {
         u32::from_le_bytes(bytes[..4].try_into().unwrap())
     }
 }
+
+pub fn read_i16_le(bytes: &[u8]) -> i16 {
+    if bytes.len() < 2 {
+        0
+    } else {
+        i16::from_le_bytes(bytes[..2].try_into().unwrap())
+    }
+}