Change modules directory for MSVC 17.5

Author: cpp-tutor

modules/01-hellow.cpp

@@ -1,6 +1,6 @@
 // 01-hellow.cpp : prints a line of text to the console
 
-import std.core;
+import std;
 using namespace std;
 
 int main() {

modules/01-title.cpp

@@ -1,6 +1,6 @@
 // 01-title.cpp : output the title page of a well-known book
 
-import std.core;
+import std;
 using namespace std;
 
 int main() {

modules/02-assign.cpp

@@ -1,6 +1,6 @@
 // 02-assign.cpp : assign to local variables
 
-import std.core;
+import std;
 using namespace std;
 
 int main() {

modules/02-constants.cpp

@@ -1,6 +1,6 @@
 // 02-constants.cpp : introducing the const keyword
 
-import std.core;
+import std;
 using namespace std;
 
 const double PI = 3.14159265358979;

modules/02-constexpr.cpp

@@ -1,6 +1,6 @@
 // 02-constexpr.cpp : introducing the constexpr keyword
 
-import std.core;
+import std;
 using namespace std;
 
 const double PI1 = acos(-1.0);     // acos is not (yet) constexpr

modules/02-height.cpp

@@ -1,6 +1,6 @@
 // 02-height.cpp : define the same variable name in two different namespaces
 
-import std.core;
+import std;
 using namespace std;
 
 namespace Wonderland {

modules/02-references.cpp

@@ -1,6 +1,6 @@
 // 02-references.cpp : introducing l-value references
 
-import std.core;
+import std;
 using namespace std;
 
 int alice_age{ 9 };

modules/02-scopes.cpp

@@ -1,6 +1,6 @@
 // 02-scopes.cpp : define three variables with the same name in one program
 
-import std.core;
+import std;
 using namespace std;
 
 auto a{ 1.5f };

modules/02-swap.cpp

@@ -1,6 +1,6 @@
 // 02-swap.cpp : attempt to swap the values of an int and a double
 
-import std.core;
+import std;
 using namespace std;
 
 int main() {

modules/02-uniform.cpp

@@ -1,6 +1,6 @@
 // 02-uniform.cpp : avoid compiler error with uniform initialization and explicit narrowing cast
 
-import std.core;
+import std;
 using namespace std;
 
 int main() {