Slideshow does not load children before view

[btkostner]

The current slideshow component conditionally renders the background for the transition (v-if). This works but means that the image (or what ever) tag only gets loaded when it's that slide's turn to be visible. This causes some glitches because we can slide to an image that has yet to be loaded. In the long run, this should be replaced with v-show logic so everything can load in the background.