Merge states instead of overriding it.

Current behaviour

When I pass something like:

{
      keys: [
        {
          app: ['locale']
        }
      ],
      rehydrate: true
    }

It will override all my initial app state keys, and only fills in the locale field.

This will break my app, and forces me to choose to either sync the wholeapp key, or nothing at all. Or alternatively, make an entirely new locale reducer on the root.

Expected behaviour

The state being merged similar to how it happens in a reducer:

{
   [currentKey]: {
      ...initialState[currentKey],
      ...localStorage[currentKey]
   } 
}

[BBlackwo]

Closing this issue as it was fixed in version 6.0.0 which started doing a deep merge of the initial state and the local storage state.

[pedep]

Not sure if there is an “easy” way to have access to the initial state of all reducers, but adding an initialState object to LocalStorageConfig, and then merging this object with state and rehydratedState in the initial action might be the easiest until a better solution is found. Not sure if this solution would be satisfactory, but it solved the issues i were having. I can put up a quick PR if you think its worth the time #84

I have closed my PR again, since i think this problem could be solved by #65