List shouldnt always be subtype of list-of

[githubforced2fabad]

I am requesting pull from: https://git.sr.ht/~charje/ctype

nil is always a subtype of list-of so (coinjoin list-of nil) should become list-of. the same goes for disjoin.

list includes non-proper lists and (list-of t), which means every list is a subtype of list-of: (cons t (not null)).

patches if you like that better (eftnamed to .txt for github...):

0001-Disallow-list-being-a-subtype-of-list-of.txt
0002-Improve-conjoin-and-disjoin-of-list-of.txt