Replace most of Prelude head, last, minimum, maximum with their Safe …

[sorki]

…variants

Mostly quick git sed to find the root cause of extcuraengine: Safe.maximumNote [], layers zmax. Some of these are probably redundant and I might reset that and only keep sensible ones if we need them.

Reproducer (implicit 0.3.0.1):

cabal run exe:extcuraengine -- \
  slice \
  -l ~/git/IObjects/Tests/TwoCubes.stl \
  -o ./TwoCubes.gcode \
  -s layer_height=0.1 \
  -s machine_width=200 \
  -s machine_depth=200 \
  -s machine_height=100  \
  -s machine_nozzle_size=0.35 \
  -s material_diameter=2.85  \
  -s outer_inset_first=False \
  -s infill_sparse_density=100 \
  +RTS -N -qg -t

[julialongtin]

Slowly doing this in a different form, using Stan's recommended Slist package.