A quick release, fixing one bug and adding some performance improvements and some new collection types. Here's the changelog: * added a faster and more compact hash array mapped trie under Sasa.Collections.Trie to replace Sasa.Collections.Tree * added Sasa.Collections.FingerTree * added purity attributes throughout Sasa (for .NET 4) * expanded various test suites and documentation * added a persistent vector, Sasa.Collections.Vector * factored out Atomics.BeginRead/BeginWrite read/write protocol so it can be used in more flexible scenarios * Sasa.Dynamics.Type .MaybeMutable is now computed eagerly * added an efficient, mutable union-find data structure * fixed: Uris.UriDecode now handles the incorrect but common UTF16 encoding * moved Sasa.LockSet under Sasa.Concurrency.LockSet The Sasa.Collections.Tree type is no longer available, and is replaced by the faster and more appropriately named Sasa.Collections.Trie. The original tree was actually a trie, and I didn't