Remove redundant virtual specifiers

`grep -nr virtual | grep -v googletest | grep override > ../redundant_virtual.txt`

```python
import os

with open("../redundant_virtual.txt") as f:
    for line in f:
        print()
        line: str = line.strip()
        print(line)
        tmp = line.split(":")
        file = tmp[0].strip()
        code = tmp[-1].strip()
        print(file)
        print(code)
        new_code = code.replace("virtual ", "", 1)
        # https://superuser.com/a/802490/578501
        command = f"export FIND='{code}' && export REPLACE='{new_code}' && ruby -p -i -e \"gsub(ENV['FIND'], ENV['REPLACE'])\" {file}"
        os.system(command)
```

client/windows/InfoWindows.h

@@ -79,7 +79,7 @@ public:
 class CRClickPopup : public WindowBase
 {
 public:
-	virtual void close() override;
+	void close() override;
 	bool isPopupWindow() const override;
 
 	static std::shared_ptr<WindowBase> createCustomInfoWindow(Point position, const CGObjectInstance * specific);