Enhancement: Replace the existing comment with the new.

[ronak1009]

The feature is to replace the existing copyright header with the new.

This is because, if the file is changed, the timestamp in the copyright comments should get updated. It is manual task to select and delete the comment and then update it with the new.

Limitation: The comments created using the plugin can only be replaced. Not other.

[doi]

For the extension to know which comment blocks to be replaced, the comment blocks must have some kind of unique identifier and that will make the comment blocks dirty. Any idea?