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/IXUnityBuildsTest.cpp

@@ -0,0 +1,52 @@
+/*
+ *  IXUnityBuildsTest.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2019 Machine Zone. All rights reserved.
+ */
+
+#include "catch.hpp"
+#include <ixwebsocket/IXCancellationRequest.h>
+#include <ixwebsocket/IXConnectionState.h>
+#include <ixwebsocket/IXDNSLookup.h>
+#include <ixwebsocket/IXHttp.h>
+#include <ixwebsocket/IXHttpClient.h>
+#include <ixwebsocket/IXHttpServer.h>
+#include <ixwebsocket/IXNetSystem.h>
+#include <ixwebsocket/IXProgressCallback.h>
+#include <ixwebsocket/IXSelectInterrupt.h>
+#include <ixwebsocket/IXSelectInterruptFactory.h>
+#include <ixwebsocket/IXSetThreadName.h>
+#include <ixwebsocket/IXSocket.h>
+#include <ixwebsocket/IXSocketAppleSSL.h>
+#include <ixwebsocket/IXSocketConnect.h>
+#include <ixwebsocket/IXSocketFactory.h>
+#include <ixwebsocket/IXSocketMbedTLS.h>
+#include <ixwebsocket/IXSocketOpenSSL.h>
+#include <ixwebsocket/IXSocketServer.h>
+#include <ixwebsocket/IXUrlParser.h>
+#include <ixwebsocket/IXWebSocket.h>
+#include <ixwebsocket/IXWebSocketCloseConstants.h>
+#include <ixwebsocket/IXWebSocketCloseInfo.h>
+#include <ixwebsocket/IXWebSocketErrorInfo.h>
+#include <ixwebsocket/IXWebSocketHandshake.h>
+#include <ixwebsocket/IXWebSocketHandshakeKeyGen.h>
+#include <ixwebsocket/IXWebSocketHttpHeaders.h>
+#include <ixwebsocket/IXWebSocketMessage.h>
+#include <ixwebsocket/IXWebSocketMessageType.h>
+#include <ixwebsocket/IXWebSocketOpenInfo.h>
+#include <ixwebsocket/IXWebSocketPerMessageDeflate.h>
+#include <ixwebsocket/IXWebSocketPerMessageDeflateCodec.h>
+#include <ixwebsocket/IXWebSocketPerMessageDeflateOptions.h>
+#include <ixwebsocket/IXWebSocketSendInfo.h>
+#include <ixwebsocket/IXWebSocketServer.h>
+#include <ixwebsocket/IXWebSocketTransport.h>
+
+using namespace ix;
+
+TEST_CASE("unity build", "[unity_build]")
+{
+    SECTION("dummy test")
+    {
+        REQUIRE(true);
+    }
+}