FLs doesn't work with tibbles

[rasmus87]

Since the package is marketed as an addition to tidyverse, I think it is important all functions work with tibbles.

The function FLs() doesn't work with tibbles due to the functions use of reshape::melt(...).

The easiest fix (but not the best) is simply to replace reshape with reshape2.

The function could be rewritten to be based on tidyverse functions, to avoid problems like this.

[CWWhitney]

I switched all the reshape to reshape2 (I only used melt from that package).
The package should be rewritten to tidy package standards.
That is something I would be grateful for collaboration on.