Add update installer program (Windows only for now)

src/updater/updater.h

@@ -0,0 +1,38 @@
+#pragma once
+#include "common/progress_callback.h"
+#include "unzip.h"
+#include <string>
+#include <vector>
+
+class Updater
+{
+public:
+  Updater(ProgressCallback* progress);
+  ~Updater();
+
+  bool Initialize(std::string destination_directory);
+
+  bool OpenUpdateZip(const char* path);
+  bool PrepareStagingDirectory();
+  bool StageUpdate();
+  bool CommitUpdate();
+  void CleanupStagingDirectory();
+
+private:
+  struct FileToUpdate
+  {
+    std::string original_zip_filename;
+    std::string destination_filename;
+  };
+
+  bool ParseZip();
+
+  std::string m_destination_directory;
+  std::string m_staging_directory;
+
+  std::vector<FileToUpdate> m_update_paths;
+  std::vector<std::string> m_update_directories;
+
+  ProgressCallback* m_progress;
+  unzFile m_zf = nullptr;
+};