POS 4u keycaps

This is basically the same as:

https://www.thingiverse.com/thing:3393751

but 4 keys long, instead of 2. This will probably bind up in real world usage, but it was another request from a random internet user.

These keycaps were made using this library:
https://github.com/rsheldiii/KeyV2

My keys.scad file looks like this:
```
use

include
include
include
include
include
include

module stable (mm=12, vertical = false, type="cherry") {
//$inverted_dish = true;
$dish_type = "disabled";
$stabilizer_type = type;
$stabilizers = [
[mm+19.05, 0],
[mm, 0],
[-mm, 0],
[-mm-19.05, 0]
];
children();
}
$stem_support_type = "disabled";
//dcs_row(n=1) 4u() stable(mm=9.525) cherry() blank() bar_support() key();
//oem_row(n=3) 4u() stable(mm=9.525, type="cherry") inset(val=0) cherry() blank() bar_support() key();
//oem_row(n=3) 4u() stable(mm=9.525, type="cherry") inset(val=0) tined_stem_support() cherry() blank() bar_