Sidebar doesn't animate unless `opened` property is bound.
I was going crazy trying to figure out why my sidebar was simply popping into existence instead of smoothly sliding open like in the demo.
So I made a stackblitz to figure out what I was doing wrong: https://stackblitz.com/edit/angular-hbfacn
The only difference between the top and bottom sections is [(opened)]="_opened" on <ng-sidebar>.
This wasn't mentioned in the docs so I assume it is a bug.
This is due to a workaround for the sidebar being visible on initial load, which basically turns off animate on load and re-enables it once it's triggered to be opened/closed again.
I've yet to think of a good fix for this.
https://github.com/arkon/ng-sidebar/blob/23e651ca10cf9ea446a0ee9e60ae6d8bf523d281/src/sidebar.component.ts#L139