Fixes #91

[Satyam]

useListVals and useObjectVal now accept a transform option to convert values on reading.

[Satyam]

Updated the pull request with the changes merged so far.

This change adds a transform option to useListVals and useObjectVal hook so that the resulting object of list of objects is converted from the representation in the database to that used internally in the application. The option, if not given, does not change the current behaviour.

Since the developer will most likely need to change objects or properties within the object that cannot be represented in a JSON object, such as a date string to a Date object. If such transformation is required, then it is better done already within these hooks, compared to doing it once the values are read since it would:

• Avoid a new pass through the data while doing the conversion, saving on processing
• Avoid another memoizing of the results of the conversion, saving on memory
• Simplify the code for the developer

Additionally both hooks now accept a generic type parameter that allows the returned object or array of objects to be properly typed.

[Satyam]

Sorry, I would love to fix the conflicts, but that exceeds my GitHub knowledge.

[chrisbianca]

@Satyam thank you for this and apologies again for the delay in getting it merged. It was easier for me to apply the changes directly onto master rather than try to resolve the conflicts here. I will make sure that you get referenced in the release notes, even if it's not referenced in the commit history.

[chrisbianca]

This has now been released in https://github.com/CSFrequency/react-firebase-hooks/releases/tag/v3.0.1