Add dict-tree.el
Minor fixes to commentaries, package headers, and whitespace

* queue.el: fix description of data structure in Commentary; add Maintainer
  header.

* queue.el, heap.el, tNFA.el, trie.el, dict-tree.el: trivial whitespace fixes.
trie.el, tNFA.el, dict-tree.el: minor package header and autoload fixes

* trie.el: remove emacs version dependency.

* tNFA.el: add missing autoload cookies.

* dict-tree.el: minor change to package description, to match the other data
structure packages.
Updated dict-tree.el package to version 0.12.8