Sliver Fill Remaining Box Adapter

A flutter package providng SliverFillRemainingBoxAdapter, a sliver that fills the remaining space or shows its child, whichever is larger.

This is essentially a combination of SliverFillRemaining, which sizes its child to the remaining space even if the child wants to be larger; and SliverToBoxAdapter, which is a sliver which sizes itself to its child.

This looks something like this:

Size by Child	Filling remaining a bit	Filling entire viewport

Usage

The SliverFillRemainingBoxAdapter can be used in a similar way to other slivers, particularly SliverBoxAdapter. It hasn't been tested with ShrinkWrap set to true, and shouldn't be expected to be have well in that scenario. It also hasn't been tested when it isn't the last item in the list, or when there multiple SliverFillRemainingBoxAdapter instances.

If you have any problems please let me know by opening an issue! As this is just a side-project, I can't promise to be very quick to respond but I'll do my best.

Anyone willing to make contributions are very welcome to submit PRs.