added client version control

+ nlohmann/json library was included in the project.
+ VersionControl class was created and it checks if the client is up to date.
+ CLIENT_VERSION macro defined.

user/network/VersionControl.h

@@ -0,0 +1,19 @@
+#pragma once
+
+class VersionControl {
+public:
+	VersionControl(const char* version_tag, const wchar_t* url);
+	~VersionControl();
+
+	const char* GetCurrentVersionTag();
+	void CheckForUpdate();
+	bool IsUpToDate();
+	const char* GetLatestDownloadLink();
+private:
+	const char* latestDownloadLink;
+	bool isUpToDate;
+	const char* current_version_tag;
+	const wchar_t* requestUrl;
+private:
+	void SetIsUpToDate(bool value);
+};