Change options to be pointer structures

[nhooyr]

I feel like websocket.AcceptOptions{} and websocket.DialOptions is getting old.

I want to change the public API to accept pointers to the option structs and thus accept nil for the defaults. Nil at the end of a function is imo pretty clearly where some options structure goes. This is a relatively minor change so no major version change.

Does anyone have any strong opinions about this?

[nhooyr]

@coadler

[coadler]

I agree, would be nice to just pass nil instead of an empty struct every time.