Implement NetworkManager

For now there are two methods:

- `NETWORK:IsUrlAllowed()`: Check whether access to a certain URL is allowed.
- `NETWORK:HttpRequest()`: Perform an HTTP request.

By default access to the network is disabled for all target hosts. It
can be enabled by setting `HttpEnable=1` in the preferences. Individual
hosts have to be added to `HttpAllowHosts` as a comma separated list to
allow access.

See included docs for more details on usage.

extern/IXWebSocket-11.3.2/test/IXStrCaseCompareTest.cpp

@@ -0,0 +1,47 @@
+/*
+ *  IXStrCaseCompareTest.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2020 Machine Zone. All rights reserved.
+ */
+
+#include "IXTest.h"
+#include "catch.hpp"
+#include <iostream>
+#include <ixwebsocket/IXUrlParser.h>
+#include <string.h>
+
+using namespace ix;
+
+namespace ix
+{
+    TEST_CASE("str_case_compare", "[str_case_compare]")
+    {
+        SECTION("1")
+        {
+            using HttpHeaders = std::map<std::string, std::string, CaseInsensitiveLess>;
+
+            HttpHeaders httpHeaders;
+
+            httpHeaders["foo"] = "foo";
+
+            REQUIRE(httpHeaders["foo"] == "foo");
+            REQUIRE(httpHeaders["missing"] == "");
+
+            // Comparison should be case insensitive
+            REQUIRE(httpHeaders["Foo"] == "foo");
+            REQUIRE(httpHeaders["Foo"] != "bar");
+        }
+
+        SECTION("2")
+        {
+            using HttpHeaders = std::map<std::string, std::string, CaseInsensitiveLess>;
+
+            HttpHeaders headers;
+
+            headers["Upgrade"] = "webSocket";
+
+            REQUIRE(!CaseInsensitiveLess::cmp(headers["upGRADE"], "webSocket"));
+        }
+    }
+
+} // namespace ix