doc
release 0.14

* Transaction#subspace for convenience
* be strict about transactions that cross subspaces
* bug fix: subspace lookup waits for metatuple to arrive, if subscribed to the tag
* new examples:
    using rbtree to manage a subspace (subspaces/addr-book.rb)
    read-atomic multipartition transactions (subspaces/ramp.rb)
    distributing prime-factoring (map-reduce/prime-factor.rb)
    unique ids (uniq-id.rb)