convert most variable swaps to mem swaps

src/common/global_histogram_binarizer.rs

@@ -214,9 +214,8 @@ impl GlobalHistogramBinarizer {
 
         // Make sure firstPeak corresponds to the black peak.
         if firstPeak > secondPeak {
-            let temp = firstPeak;
-            firstPeak = secondPeak;
-            secondPeak = temp;
+
+            std::mem::swap(&mut firstPeak, &mut secondPeak);
         }
 
         // If there is too little contrast in the image to pick a meaningful black point, throw rather

src/common/reedsolomon/generic_gf_poly.rs

@@ -154,9 +154,7 @@ impl GenericGFPoly {
         let mut smallerCoefficients = self.coefficients.clone();
         let mut largerCoefficients = other.coefficients.clone();
         if smallerCoefficients.len() > largerCoefficients.len() {
-            let temp = smallerCoefficients;
-            smallerCoefficients = largerCoefficients;
-            largerCoefficients = temp;
+            std::mem::swap(&mut smallerCoefficients,&mut largerCoefficients)
         }
 
         let mut sumDiff = vec![0; largerCoefficients.len()];

src/common/reedsolomon/reedsolomon_decoder.rs

@@ -121,9 +121,7 @@ impl ReedSolomonDecoder {
         let mut a = a.clone();
         let mut b = b.clone();
         if a.getDegree() < b.getDegree() {
-            let temp = a;
-            a = b;
-            b = temp;
+            std::mem::swap(&mut a, &mut b);
         }
 
         let mut rLast = a;