Propose code-cleanups#2 (#253)

Description of the changes:

Remove redundancy
Simplify if statements

src/CalcManager/CalculatorHistory.cpp

@@ -34,15 +34,13 @@ unsigned int CalculatorHistory::AddToHistory(_In_ shared_ptr<CalculatorVector <p
 
 unsigned int CalculatorHistory::AddItem(_In_ shared_ptr<HISTORYITEM> const &spHistoryItem)
 {
-    int lastIndex;
-
     if (m_historyItems.size() >= m_maxHistorySize)
     {
         m_historyItems.erase(m_historyItems.begin());
     }
 
     m_historyItems.push_back(spHistoryItem);
-    lastIndex = static_cast<unsigned>(m_historyItems.size() - 1);
+    unsigned int lastIndex = static_cast<unsigned>(m_historyItems.size() - 1);
     return lastIndex;
 }
 

src/CalcManager/CalculatorManager.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
 #include "pch.h"
@@ -360,7 +360,7 @@ namespace CalculationManager
     /// <param name = "serializedPrimaryDisplay">Serialized Rational of primary display</param>
     void CalculatorManager::DeSerializePrimaryDisplay(const vector<long> &serializedPrimaryDisplay)
     {
-        if (serializedPrimaryDisplay.size() == 0)
+        if (serializedPrimaryDisplay.empty())
         {
             return;
         }