Add ability to hide subtopics of non active topics

[dkhunt27]

This is a feature request.

Would be cool if the sidebar had the ability to display/hide the subtopics of non active topics. This would help to reduce the size of the side bar and make finding the topics a little easier. And then when in a topic, then display the active subtopics.

I did this in one of my deploys by adding the following to Sidebar.vue. It works, but probably would need to add a nice collapse transition to it and maybe an option to enable/disable it because others might not want this

(if i can add those I will send a PR... but here is what I have now)

data() {
return {
activeTopic: {}
}
},
methods: {
toggleActiveTopic(topic) {
this.activeTopic = topic;
}
...

once again, thanks for the great theme!

[samuelhorn]

Will look in to this when i have the time, thank!