almost working implementation of microKanren from the paper
that is a lot better now
move reification to value objects, fix some minor bugs, add examples
add failing example case
add another simplified failing case based on disj_plus
introduce monadic stream to solve all problems
rename walk() to lookup()
Revert "rename walk() to lookup()"

This reverts commit fed3248e2a85a63e22395933432c427f1dbd3421.
add todo item for iter
rename argument in cons/first/rest to $list
add todo for pair abstraction
update LICENSE to 2014 as it only just was really created
remove phpunit.xml.dist for now
update README with a high-level conde example
use EmptyIterator instead of ArrayIterator([])
move examples into test.php
check for null explicitly when looking up values (allows unifying with empty array)
add all() as an alias fr conj_plus
introduce pairs that unify with arrays so that we can membero
reify pairs (primitive implementation)