[m-rev.] splitting io.m

[Peter Wang]

Hi,

Would there be any opposition to splitting io.m into multiple modules,
while maintaining the interface?  Most of the predicates have the
exported Mercury predicate wrapping private foreign_procs.  I'm thinking
the foreign_procs can be moved into submodules.  The submodules might be

    io.error
    io.read
    io.write
    io.seek
    io.file_type
    io.rename
    io.file_time
    io.environ
    io.system
    io.make_temp
    ...

Peter