Allow root to be a folder

[mavrothal]

In frugalified puppies vmlinuz, ucode.cpio and frugalify can be anywhere and their location can be defined by the bootloader and the kernel cml. However, upper and all SFSs must be at the root of PARTUUID.
Would be handy if the SFSs/upper location could be bootloader defined, or simply accept the frugalify location as root and look only there.
This way frugalified pups could be more flexible and be installed together with other PUPs/OSs in the same partition.

PS: Labels are not active in this repo so I can not label this issue as "Enhancement"

[mavrothal]

from puppy forum
it won't be hard to add support for psubdir= or whatever. So far, nobody asked for this

Looks like #1 as well as #2 that needs a simple yes/no answer - so minimal time- were not seen.
Should we move all discussions/issues to the forum and keep github for the building process only?