tidy: contract the namespaces

alib2algo/src/string/properties/PeriodicPrefix.h

@@ -5,9 +5,7 @@
 #include <string/LinearString.h>
-namespace string {
-
-namespace properties {
+namespace string::properties {
 class PeriodicPrefix {
 public:
@@ -58,6 +56,4 @@ ext::pair < size_t, size_t > PeriodicPrefix::construct ( const string::LinearStr
 	return ext::make_pair ( maxlen, maxper );
 }
-} /* namespace properties */
-
-} /* namespace string */
+} /* namespace string::properties */