layered: Actually change the area index for hyperedge splitting.

[soerendomroes]

Fixes #944

Thanks @Quantum64

[Quantum64]

I'm currently reimplementing the ELK Layered algorithm in Rust and I'll be sure to report any other weirdness I catch as well.

[soerendomroes]

I'm currently reimplementing the ELK Layered algorithm in Rust and I'll be sure to report any other weirdness I catch as well.

Thank you. Do you have any particular reason to reimplement ELK in Rust?

[Quantum64]

I'm currently reimplementing the ELK Layered algorithm in Rust and I'll be sure to report any other weirdness I catch as well.

Thank you. Do you have any particular reason to reimplement ELK in Rust?

I'm experimenting with using it in a Rust application that contains a graph editor. Using the Java implementation directly (perhaps as a daemon that a native app connects to) isn't possible due to particular implementation restrictions on this app. Plus it's just fun to go through this algorithm and really learn how it works.

Not to worry - I will be sure to open source my implementation prior to its distribution in any software product in compliance with the Eclipse Public License.