Dynamic columns as a function prop

[levibuzolic]

Quick feature request, this makes it much easier/quicker to provide dynamic column counts without needing to measure the container in user-code. I think this is a nice interface and feels appropriate given react-photo-gallery is already doing the measurement.

I've bumped the minor version to indicate new functionality which should be non-breaking.

[coveralls]

Coverage increased (+0.2%) to 91.391% when pulling a37ef73 on levibuzolic:columns-function into dfeff66 on neptunian:master.

[levibuzolic]

Also removed the package-lock.json which is long long out-of-date and it seems the yarn.lock is more recent.

Ideally projects should use either a yarn.lock or a package-lock.json not both -- as it leads to package inconsistencies.

For example if you currently try and npm install you'll end up with vastly different dependencies, resulting in tests failing.

[levibuzolic]

Noticed these setStates were setting the width as a string, which doesn't seem correct, so i've updated them.

[neptunian]

Great idea! I was thinking instead of creating a new Code Sandbox example we can just adjust this already existing one to stop using the Measure component: https://codesandbox.io/s/ll7ym48027 . I can change it after it's published.

[levibuzolic]

@neptunian code sandbox examples removed, thanks! 👍