Sqlarfs: Use sqlite as fuse back end

I really like the idea, database as fs backend, but sqlarfs functions is very limited, really hope it get more attentions.

BTW, save files in sqlite is better when there is a lot small files [0], use sqlite as file format[1] is also quite good.

[0] https://www.sqlite.org/fasterthanfs.html [1] https://www.sqlite.org/appfileformat.html