Rework the encoder, replace all unsafe code

src/pixel.rs

@@ -8,6 +8,15 @@ impl<const N: usize> Pixel<N> {
         Self([0; N])
     }
 
+    #[inline]
+    pub fn read(&mut self, s: &[u8]) {
+        let mut i = 0;
+        while i < N {
+            self.0[i] = s[i];
+            i += 1;
+        }
+    }
+
     #[inline]
     pub const fn as_rgba(self, with_a: u8) -> Pixel<4> {
         let mut i = 0;