Add customOrder and disableOptimalOrderHeuristic

[futpib]

This allows users to customize ordering algorithm. May help address #189, #201 and other

[FelixSchwarzmeier]

@lutzroeder could this PR please be merged for the next release? Being able to customize the order is a highly requested feature for my project.

[dlangerenken]

@lutzroeder any updates?

[JoshuaeKaiser]

Same here, quite an important update.

[apdsm]

Would love if this could get merged!

[Rishav159]

@lutzroeder Any update on this? This is an important feature for my project.

[TEJATJ]

Yes this is a good and a needed feature. For dynamic graph-building/flow-creations an option like this would help minimise the frequent ordering of nodes.

[SaiSumanthLokinindi]

Now as the repo is being maintained, @rustedgrail can we expect this PR to be merged?

[rustedgrail]

I'll take a look at the branch soon, but at a cursory glance, it looks fine.

[futpib]

[rustedgrail]

Thank you for your help and for our patience

[judehunter]

Hi, this looks great. Could we get some guidance on how to use this to achieve some common use cases, please? @rustedgrail @futpib

[dongtc]

Have a doubt，seems it doesn't merged into master ? https://github.com/dagrejs/dagre/blob/master/lib/layout.js#L29