rename `has_sparsestruct` to `hassparsestruct`

[oxinabox]

I was reminded by JuliaDiff/BlueStyle#36

If this is to go into Base then the base convention is not to put _ after has
see:
hasfield haskey hasmethod hasproperty

[ChrisRackauckas]

Sure. It'll need a major release though.

[matbesancon]

It starts to read badly IMO, due to the combination of no separator and abbreviated words. Could we at least do something like `hassparse_structure`?

…

On Tue, Oct 8, 2019, 06:28 Christopher Rackauckas ***@***.***> wrote: Sure. It'll need a major release though. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#25>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AB2FDMUUIPGL7JHJOZ3PPGDQNQEADANCNFSM4I544CKQ> .