MaterialToast.fireToast could return "this"

[gkresic]

Feature request.

For toasts with unlimited duration (lifeMillis < 0), we have to call .close() at some point so we need reference to opened toast.

Now, we have to create and fire such toast it in two steps:

MaterialToast toast = new MaterialToast();
toast.toast(message, -1);

With .fireToast(...) variants returning created toast, code could look even simpler:

MaterialToast toast = MaterialToast.fireToast(message, -1);

Change is rather trivial, but if needed, I could make a PR.

[kevzlou7979]

Will create a branch 2.4 then you can base off with that branch for the PR.