Add support for packed clients (#802)

* First iteration of pack reader and interface

* Fix memory leak and remove logs

* Complete packed asset interface and begin on file loading replacement

* Implement proper BinaryIO error

* Improve AssetMemoryBuffer for reading and implement more reading

* Repair more file loading code and improve how navmeshes are loaded

* Missing checks implementation

* Revert addition of Manifest class and migration changes

* Resolved all feedback.

dCommon/dClient/AssetManager.h

@@ -0,0 +1,78 @@
+#pragma once
+
+#include <string>
+#include <vector>
+#include <unordered_map>
+#include <filesystem>
+
+#include "Pack.h"
+#include "PackIndex.h"
+
+enum class eAssetBundleType {
+	None,
+	Unpacked,
+	Packed
+};
+
+struct AssetMemoryBuffer : std::streambuf {
+	char* m_Base;
+	bool m_Success;
+
+	AssetMemoryBuffer(char* base, std::ptrdiff_t n, bool success) {
+		m_Base = base;
+		m_Success = success;
+		if (!m_Success) return;
+		this->setg(base, base, base + n);
+	}
+
+	pos_type seekpos(pos_type sp, std::ios_base::openmode which) override {
+		return seekoff(sp - pos_type(off_type(0)), std::ios_base::beg, which);
+	}
+
+	pos_type seekoff(off_type off,
+		std::ios_base::seekdir dir,
+		std::ios_base::openmode which = std::ios_base::in) override {
+		if (dir == std::ios_base::cur)
+			gbump(off);
+		else if (dir == std::ios_base::end)
+			setg(eback(), egptr() + off, egptr());
+		else if (dir == std::ios_base::beg)
+			setg(eback(), eback() + off, egptr());
+		return gptr() - eback();
+	}
+
+	void close() {
+		delete m_Base;
+	}
+};
+
+class AssetManager {
+public:
+	AssetManager(const std::string& path);
+	~AssetManager();
+
+	std::filesystem::path GetResPath();
+	eAssetBundleType GetAssetBundleType();
+
+	bool HasFile(const char* name);
+	bool GetFile(const char* name, char** data, uint32_t* len);
+	AssetMemoryBuffer GetFileAsBuffer(const char* name);
+
+private:
+	void LoadPackIndex();
+	void UnpackRequiredAssets();
+
+	// Modified crc algorithm (mpeg2)
+	// Reference: https://stackoverflow.com/questions/54339800/how-to-modify-crc-32-to-crc-32-mpeg-2
+	inline uint32_t crc32b(uint32_t base, uint8_t* message, size_t l);
+
+	bool m_SuccessfullyLoaded;
+
+	std::filesystem::path m_Path;
+	std::filesystem::path m_RootPath;
+	std::filesystem::path m_ResPath;
+
+	eAssetBundleType m_AssetBundleType = eAssetBundleType::None;
+
+	PackIndex* m_PackIndex;
+};