Add placeholders (%@,%s...) examples and fix font extension filename

SampleFiles/Strings/Generated/en.lproj/sampleStrings.strings

@@ -6,14 +6,19 @@
 
 /********** Webservice **********/
 
-"param_lang" = "en"
+"param_lang" = "en";
 
 
 /********** Generic **********/
 
-"generic_back" = "Back"
+"generic_back" = "Back";
 
-"generic_loading_data" = "Loading data..."
+"generic_loading_data" = "Loading data...";
 
-"generic_welcome_firstname_format" = "Welcome \"%@\" !"
+"generic_welcome_firstname_format" = "Welcome \"%@\" !";
+
+
+/********** Placeholders **********/
+
+"placeholders_test_one" = "You %%: %2$@ %1$@ Age: %3$d";