What I need to do in v0.1-DP3

[DrewNaylor]

See also: #195. That issue has some stuff I need to transfer to this one, or a later one (mainly the blur effect and a few other things; that might be a later version).

I'm writing some of this out now so I don't forget.

• Use the tile layout grid from TilesGrid and modify it so tiles will be properly positioned (requires merging the properties of those tiles into my tiles so they can work with it)
• Fix the All Apps list choppy/slow scrolling (Scrolling the All Apps list can be slow/choppy on the PinePhone due to not caching the Icon key value from .desktop files (will be changed in v0.1-DP3). #211)
• My todo list for the next time I work on this (TODO list for the next time I work on this. #248)
• Hide the contents of files when they're too far away from the view, like how games do culling (To improve performance, hide tile contents or even tiles themselves when they're far enough away from the visible area. #240)
• Ensure the appbar is sized correctly when in landscape mode and the appbar is on the side of the app (may take more work to properly layout everything and have the appbar drawer act more like what most apps have instead of popping up from the bottom).