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/ixwebsocket/IXStrCaseCompare.cpp

@@ -0,0 +1,37 @@
+/*
+ *  IXStrCaseCompare.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2020 Machine Zone. All rights reserved.
+ */
+
+#include "IXStrCaseCompare.h"
+
+#include <algorithm>
+#include <locale>
+
+namespace ix
+{
+    bool CaseInsensitiveLess::NocaseCompare::operator()(const unsigned char& c1,
+                                                        const unsigned char& c2) const
+    {
+#if defined(_WIN32) && !defined(__GNUC__)
+        return std::tolower(c1, std::locale()) < std::tolower(c2, std::locale());
+#else
+        return std::tolower(c1) < std::tolower(c2);
+#endif
+    }
+
+    bool CaseInsensitiveLess::cmp(const std::string& s1, const std::string& s2)
+    {
+        return std::lexicographical_compare(s1.begin(),
+                                            s1.end(), // source range
+                                            s2.begin(),
+                                            s2.end(),         // dest range
+                                            NocaseCompare()); // comparison
+    }
+
+    bool CaseInsensitiveLess::operator()(const std::string& s1, const std::string& s2) const
+    {
+        return CaseInsensitiveLess::cmp(s1, s2);
+    }
+} // namespace ix