Custom duration Snackbar

[maxmijn]

Thanks a lot for this library!

I was wondering if it is possible to set a custom duration for the Snackbar. 3 seconds (the LENGTH_LONG) is too short for my needs and indefinite is not an option.

Cheers

[cooperka]

Based on an initial check online it looks like Android's Snackbar supports this -- https://stackoverflow.com/a/44009407/763231

I would happily accept a PR adding this feature to this library. Thanks @maxmijn.