Support customized redis key prefix

[dcb9]

Fixed key prefix limits the project potential in a complex situation

[ovdienkonikolai]

Hello, this issue is relevant to us, we would like to see these changes in the main branch. What's preventing the merge?

[freddierice]

I'm also interested in this feature.

I'm not a maintainer, but it looks like you're breaking the type signature of the Limiter constructor. Another approach could be to add limiter options, for example:

type LimiterOpt func(*Limiter)
func NewLimiter(rdb rediser, opts ...LimiterOpt) *Limiter {
     ...
}

[dcb9]

@freddierice I totally agree with you, I'll change the approach to option pattern without changing default behavior.