(surprising/inconsistent) handling of begin/end attributes in slice

[jwaldmann]

This is fine (selected part of sample gets cut in half):

ghci> chop 2 $ s "led" # begin 0.03 # end 0.86
(0>½)|begin: 3.0e-2f, end: 0.44499999999999995f, s: "led"
(½>1)|begin: 0.44499999999999995f, end: 0.86f, s: "led"

but this is surprising (does not cut the sample):

ghci> slice 2 0 $ s "led" # begin 0.03 # end 0.86
(0>1)|begin: 3.0e-2f, end: 0.86f, s: "led"

see discussion at https://club.tidalcycles.org/t/surprising-inconsistent-handling-of-begin-end-attributes-in-slice/5052/1