Remove non-existant nuget files from solution
Fix nuget command - after all, nuget isn't in the repo anymore.
Implement & test a more dense serialization that allows preallocating node arrays.

--HG--
rename : A-vs-An/WikipediaAvsAnTrieExtractorTest/SerializeToDenseHexTest.cs => A-vs-An/WikipediaAvsAnTrieExtractorTest/DenseSerializerTest.cs
rename : A-vs-An/WikipediaAvsAnTrieExtractorTest/SerializeToDenseHexTest.cs => A-vs-An/WikipediaAvsAnTrieExtractorTest/NodeEqualityComparer.cs
rename : A-vs-An/WikipediaAvsAnTrieExtractorTest/SerializeToDenseHexTest.cs => A-vs-An/WikipediaAvsAnTrieExtractorTest/SerializerTest.cs