Open source Gantt chart library?

Anyone know an open source and well maintained JavaScript Gantt chart library?

There are many paid options ($1000+ /yr) (bryntum, neuronetio, dhtmlx, Syncfusion, AnyChart + many more) which aren't feasible for a bootstrapped company.

Specifically I'm looking for:

• dependencies between tasks
• child tasks
• custom rendering
• draggable tasks
• clickable tasks.

At some point I'll have to look into forking one of the open source ones and adding what I'm looking for. Btw this is for Portabella, currently we're on Frappe Gantt which is lacking a lot