- improve symlink cleaning to work with different recoveries' `ls -al` output formatting.
- make symlink creation more intelligent/futureproof to work with different busybox binaries' included applets list output length.
- make systemless install "smart" by only creating applet symlinks in /su/bin for those applets that don't exist in /system/bin to avoid conflicts with toybox/toolbox versions.
The last item should help users who were seeing WiFi Calling disrupted after they installed Busybox to /su/bin, as well as issues with AdAway's webserver and root explorers like FX File Explorer being unable to remount /system rw, (to name only a few, I'm sure). /su/bin was designed to take precedence over /system/bin whereas /system/xbin does not, so by installing to /su/bin busybox was replacing some system functions it wouldn't in /system/xbin, which understandably can break some things.