library/io.m:
Add predicates io.write_array/[56] which are are similar to
io.write_list but work on arrays and do _not_ require converting
the array into a list first.
library/array2d.m:
Add array2d.is_empty/1.
NEWS:
Announce the above additions.
tests/hard_coded/Mmakefile:
tests/hard_coded/write_array.{m,exp}:
Add a test for write_array.
tests/hard_coded/test_array2d.{m,exp}:
Extend this test to cover is_empty/1.
