Margins are limited about yatta

[LGUG2Z]

For the outer margins (around the entire display), this is currently hard coded (https://github.com/LGUG2Z/yatta/blob/master/yatta/src/desktop.rs#L532).

Maybe this could be dropped to 15 and still look okay, but when dropped further than that, the margins stop changing equally between the vertical and the horizontal axis and it doesn't look great. I've attached an example to show what I mean when this value is reduced even to 5.

I have no objections to making the PADDING variable modifiable via yattac so that this can be set per-user in their configuration (similar to the yattac.exe gap-size N option to set the gaps between the windows), however, digging in to how to get the outer margin padding to stay consistent at lower values is not a rabbit hole I'm willing to go down myself.

[LGUG2Z]

@Furezuu With the latest commit to the master branch, you will be able to specify yattac.exe padding-size N in your AHK configuration to set the padding around the screen to the value of your choice. 🎉