Rename from string to from slice and fuck utf8

src/ijvmreader.rs

@@ -21,10 +21,10 @@ impl IJVMReader {
         })
     }
 
-    pub fn new_from_string(source: String) -> IJVMReader {
+    pub fn new_from_slice(source: &[u8]) -> IJVMReader {
         IJVMReader {
             pointer: 0,
-            source: source.into_bytes(),
+            source: source.to_vec(),
         }
     }
 }