No more SEGV. Omits invalid (default) values. Logs unconditional DEBUG
output, to be removed before merging into development. Still missing
cf_cmp_ functions to prune out default values.
Improved config Object Model iterator logic to barf on internal NULL
nodes.
Replace 'parsefunc' (cf_opt_foo) function arguments in schema
declarations with 'repr' (foo) names, which are used to declare
cf_opt_foo and cf_fmt_foo.
Config Object Model parser now returns bitmask result of CFxxx flags and only
allocates root node if the config file is non-empty.
Added emalloc_zero().