Improve performance with `fixedrate=true`

In the calculation of recurrence matrices with fixed recurrence rate there is the issue commented in #46 (indirectly calling distancematrix, which is expensive):

https://github.com/JuliaDynamics/RecurrenceAnalysis.jl/blob/2961a32b29e41ea1e3dc3d63f67e29d74948e5ab/src/matrices.jl#L220-L222

A function that gives the same result as quantile(distancematrix(x,y), ε) without calling distancematrix would help.

---

Want to back this issue? Post a bounty on it! We accept bounties via Bountysource.