Timeline has been moved into its own package now so it would be nice to have it added as a dependency. Maybe in a upm_2019_3 branch?
Library/PackageCache/jp.keijiro.klak.timeline.particle-system-control@2806049fc31f466c1d619dadf67935b9856358c5/Runtime/ParticleSystemControlClip.cs(6,19): error CS0234: The type or namespace name 'Timeline' does not exist in the namespace 'UnityEngine' (are you missing an assembly reference?)
Timeline has been moved into its own package now so it would be nice to have it added as a dependency. Maybe in a upm_2019_3 branch?