std: avoid need for casting in hexavigesimal

plus use constexpr to define the compile time constant

alib2std/src/extensions/hexavigesimal.cpp

@@ -4,7 +4,7 @@
 namespace ext {
 namespace {
-	static const int BASE26 = 26;
+	static constexpr int BASE26 = 26;
 }
 unsigned fromBase26( const std::string & rep ) {
@@ -22,8 +22,8 @@ unsigned fromBase26( const std::string & rep ) {
 std::string toBase26( unsigned n ) {
 	std::string name;
 	do {
-		name += ( char )( n % BASE26 + 'A' );
-		n = n / BASE26;
+		name.push_back ( n % BASE26 + 'A' );
+		n /= BASE26;
 	} while (n > 0);
 	return std::string( name.rbegin( ), name.rend( ) );
@@ -44,7 +44,7 @@ std::string bijectiveToBase26(unsigned n) {
 	std::string name;
 	while(n > 0) {
 		--n;
-		name += (char) (n % BASE26 + 'A');
+		name.push_back ( n % BASE26 + 'A' );
 		n /= BASE26;
 	}
 	return std::string(name.rbegin(), name.rend());