update to modern gdc compatibility

.gitignore

@@ -0,0 +1,4 @@
+init/init
+factorial/factorial
+datatypes/datatypes
+appending/appending

datatypes/datatypes.d

@@ -34,7 +34,7 @@ int main()
     writefln("char (%d)\twchar (%d)\tdchar (%d)",
             char.sizeof, wchar.sizeof, dchar.sizeof);
 
-    writefln();
+    writefln("");
     writefln("char min: %d\tmax: %d", char.min, char.max);
     writefln("wchar min: %d\tmax: %d", wchar.min, wchar.max);
 

init/init.d

@@ -2,10 +2,10 @@
 import std.stdio;
 
 int magicNumber = 42;
-char[] password = "sesame";
+string password = "sesame";
 
 void main()
 {
-    writefln("Magic number: ", magicNumber);
-    writefln("Password: ", password);
+    writefln("Magic number: %s", magicNumber);
+    writefln("Password: %s", password);
 }