Event bus system

[Strongleong]

It will solve several problems.

• It will much easier to implement CLI: addition/exctraction progress bar CLI: addition/exctraction progress bar #31, because otherwise we need to redo addition/excratcion logic so it can yield back to the caller what file is processing/processed at this moment. With event bus we can register listener for events FileAdded/FileExtraced that would print in CLI or show some progress bar in GUI and just fire those events in the lib.

• As @romibi said in Backup functionality and its Tests needs refactoring and maybe has some bugs Backup functionality and its Tests needs refactoring and maybe has some bugs #38:

Maybe using callbacks in Scrap Packed File "DoOnBeforeSave", "DoOnSaveSuccess" and "DoOnSaveError"?

It can be done with same event bus system

[Strongleong]

It appears that C# already have pub/sub system with delegate and event keywords 😅