Add README and LICENSE

LICENSE.md

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+
+Copyright 2012 Kristopher Michael Kowal. All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to
+deal in the Software without restriction, including without limitation the
+rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+sell copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+IN THE SOFTWARE.
+

README.md

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+A binary splay tree is a balanced binary tree that rotates the most
+frequently used items toward the root such that they can be accessed the
+most quickly.  This CommonJS package includes a `SplaySet` and
+`SplayMap` in `splay-set` and `splay-map` modules.
+
+Additionally, this implementation applies the insight that any Map can
+be implemented in terms of a Set provided that you can override
+functions that operate on the values within that set.  All of the splay
+tree reference implementations opted to implement a map interface
+instead.
+
+Both `SplaySet` and `SplayMap` implement a `log` function which can
+produce NPM-style visualizations of the internal state of the splay
+tree.
+
+```
+> set.log(SplaySet.ascii)
+  .-+ -3
+  | '-- -2
+.-+ -1
++ 0
+| .-- 1
+'-+ 2
+  '-- 3
+```
+
+```
+> set.log(SplaySet.unicodeRound)
+  ╭━┳ -3
+  ┃ ╰━━ -2
+╭━┻ -1
+╋ 0
+┃ ╭━┳ 1
+┃ ┃ ╰━━ 2
+╰━┻ 3
+```
+
+## References
+
+- a SplayTree impementation buried in Fedor Indutny’s super-secret
+  [Callgrind](https://github.com/indutny/callgrind.js). This
+  implementation uses parent references.
+- a SplayTree implementation adapted by [Paolo
+  Fragomeni](https://github.com/hij1nx/forest) from the V8 project and
+  based on the top-down splaying algorithm from "Self-adjusting Binary
+  Search Trees" by Sleator and Tarjan. This does not use or require
+  parent references, so I favored it over Fedor Indutny’s style.
+- the interface of ECMAScript harmony [simple maps and
+  sets](http://wiki.ecmascript.org/doku.php?id=harmony:simple_maps_and_sets)
+- a SplayTree implementation from [JavaScript data
+  structures](derrickburns/Javascript-Data-Structures) mainted by
+  Derrick Burns that supports change-resilient iterators and a
+  comprehensive set of introspection functions.
+
+## Future work
+
+- tests
+- docs
+- incorporate all array-like methods
+- incorporate iterability
+- incorporate comprehensive introspection functions for slicing ranges
+- hash string map and set, using underlying object
+- relax unique content constraint on splay trees to implement splay
+  list and splay multi-map
+- LRU cache sets and maps
+- ARC cache sets and maps
+- linked list types
+- trie set and map
+- immutable set and map structures using hash tries
+- heap
+- binary heap
+- observable variants of all collection types
+- alternative module systems song and dance
+