many small rustifications

src/qrcode/decoder/decoder.rs

@@ -158,11 +158,10 @@ fn decode_bitmatrix_parser_with_hints(
     let dataBlocks = DataBlock::getDataBlocks(&codewords, version, ecLevel)?;
 
     // Count total number of data bytes
-    let mut totalBytes = 0usize;
-    for dataBlock in &dataBlocks {
-        // for (DataBlock dataBlock : dataBlocks) {
-        totalBytes += dataBlock.getNumDataCodewords() as usize;
-    }
+    let  totalBytes = dataBlocks.iter().fold(0, |acc,dataBlock| {
+        acc + dataBlock.getNumDataCodewords() as usize
+    });
+    
     let mut resultBytes = vec![0u8; totalBytes];
     let mut resultOffset = 0;
 

src/qrcode/detector/finder_pattern_finder.rs

@@ -686,11 +686,10 @@ impl FinderPatternFinder {
         // vary too much. We arbitrarily say that when the total deviation from average exceeds
         // 5% of the total module size estimates, it's too much.
         let average = totalModuleSize / max as f32;
-        let mut totalDeviation = 0.0;
-        for pattern in &self.possibleCenters {
-            // for (FinderPattern pattern : possibleCenters) {
-            totalDeviation += (pattern.getEstimatedModuleSize() - average).abs();
-        }
+        let  totalDeviation = self.possibleCenters.iter().fold(0.0, |acc, pattern| {
+acc + (pattern.getEstimatedModuleSize() - average).abs()
+        });
+        
         totalDeviation <= 0.05 * totalModuleSize
     }
 

src/qrcode/encoder/encoder.rs

@@ -529,7 +529,7 @@ pub fn getNumDataBytesAndNumECBytesForBlockID(
             + ((num_data_bytes_in_group2 + numEcBytesInGroup2) * num_rs_blocks_in_group2)
     {
         return Err(Exceptions::WriterException(Some(
-            "Total bytes mismatch".to_owned(),
+            "total bytes mismatch".to_owned(),
         )));
 
         // throw new WriterException("Total bytes mismatch");