Introduced utilities to gradually replace utils. (#2651)

* Replace current levenshtein with much faster implementation.
* Remove usage of alias to simplify code for VS 2013.

src/common/utilities.cpp

@@ -0,0 +1,63 @@
+#include "utilities.hpp"
+
+#include <chrono>
+#include <string>
+#include <algorithm>
+#include <iostream>
+#include <numeric> //iota
+
+struct cScopeTimer::sPimpl {
+    std::chrono::steady_clock::time_point start;
+    std::chrono::steady_clock::time_point end;
+    
+    sPimpl()
+    {
+        start = std::chrono::steady_clock::now();
+    }
+    
+    ~sPimpl(){
+        end = std::chrono::steady_clock::now();
+        std::chrono::microseconds diff = std::chrono::duration_cast<std::chrono::microseconds>(end - start);
+        std::cout << " took=" << diff.count() << "ms !\n";
+    }
+};
+
+cScopeTimer::cScopeTimer() 
+	: aPimpl(new sPimpl())
+{}
+
+/**
+ * Calculates the Levenshtein distance of two strings.
+ * @author http://en.wikibooks.org/wiki/Algorithm_Implementation/Strings/Levenshtein_distance#C.2B.2B
+ * comparison test was done here http://cpp.sh/2o7w
+ */
+int levenshtein(const std::string &s1, const std::string &s2)
+{
+	// To change the type this function manipulates and returns, change
+	// the return type and the types of the two variables below.
+	int s1len = static_cast<int>(s1.size());
+	int s2len = static_cast<int>(s2.size());
+	
+	auto column_start = (decltype(s1len))1;
+	
+	auto column = new decltype(s1len)[s1len + 1];
+	std::iota(column + column_start, column + s1len + 1, column_start);
+	
+	for (auto x = column_start; x <= s2len; x++) {
+		column[0] = x;
+		auto last_diagonal = x - column_start;
+		for (auto y = column_start; y <= s1len; y++) {
+			auto old_diagonal = column[y];
+			auto possibilities = {
+				column[y] + 1,
+				column[y - 1] + 1,
+				last_diagonal + (s1[y - 1] == s2[x - 1]? 0 : 1)
+			};
+			column[y] = std::min(possibilities);
+			last_diagonal = old_diagonal;
+		}
+	}
+	auto result = column[s1len];
+	delete[] column;
+	return result;
+}