Refactor/actionbase

[greymistcube]

No description provided.

[s2quake]

How about using nameof(InfoAction.GetInfo) instead of literal strings.

[s2quake]

How about a pattern like below?

        void IAction.LoadPlainValue(IValue plainValue)
        {
            if (_isLoaded)
            {
                throw new InvalidOperationException("Action is already loaded.");
            }

            Dictionary dict = (Dictionary)plainValue;
            _name = (Text)dict["type_id"];
            _exec = (Text)dict["exec"];
            _args = dict["args"];
            _isLoaded = true;
        }

It has two advantages: limited access and avoiding duplicate calls.