simplifying a function

Dramatic simplification of legacy code by separating code and data and applying some later C++.
Function removed from Application.cpp as it was in a anonymous namespace and could not easily be subjected to unit testing.
Added ProgramOptionsUtilities.h

tests/src/App/Application.cpp

@@ -0,0 +1,38 @@
+#include "gtest/gtest.h"
+#define FC_OS_MACOSX 1
+#include "App/ProgramOptionsUtilities.h"
+
+using namespace App::Util;
+
+using Spr = std::pair<std::string, std::string>;
+
+TEST(ApplicationTest, fCustomSyntaxLookup){
+    Spr res {customSyntax("-display")};
+    Spr exp {"display", "null"};
+    EXPECT_EQ(res,exp);
+};
+TEST(ApplicationTest, fCustomSyntaxMac){
+    Spr res {customSyntax("-psn_stuff")};
+    Spr exp {"psn", "stuff"};
+    EXPECT_EQ(res,exp);
+};
+TEST(ApplicationTest, fCustomSyntaxWidgetCount){
+    Spr res {customSyntax("-widgetcount")};
+    Spr exp {"widgetcount", ""};
+    EXPECT_EQ(res,exp);
+}
+TEST(ApplicationTest, fCustomSyntaxNotFound){
+    Spr res {customSyntax("-displayx")};
+    Spr exp {"", ""};
+    EXPECT_EQ(res,exp);
+};
+TEST(ApplicationTest, fCustomSyntaxAmpersand){
+    Spr res {customSyntax("@freddie")};
+    Spr exp {"response-file", "freddie"};
+    EXPECT_EQ(res,exp);
+};
+TEST(ApplicationTest, fCustomSyntaxEmptyIn){
+    Spr res {customSyntax("")};
+    Spr exp {"", ""};
+    EXPECT_EQ(res,exp);
+};