Split up extensions into their own classes.

Implement trivial Node count extension for linqpad usage.

--HG--
rename : A-vs-An/WikipediaAvsAnTrieExtractor/MutableNodeExtensions.cs => A-vs-An/WikipediaAvsAnTrieExtractor/DenseHexExtension.cs
rename : A-vs-An/WikipediaAvsAnTrieExtractor/MutableNodeExtensions.cs => A-vs-An/WikipediaAvsAnTrieExtractor/IncrementPrefixExtensions.cs
rename : A-vs-An/WikipediaAvsAnTrieExtractor/MutableNodeExtensions.cs => A-vs-An/WikipediaAvsAnTrieExtractor/NodeCountExtension.cs
rename : A-vs-An/WikipediaAvsAnTrieExtractor/MutableNodeExtensions.cs => A-vs-An/WikipediaAvsAnTrieExtractor/ReadableSerializationExtension.cs
rename : A-vs-An/WikipediaAvsAnTrieExtractor/MutableNodeExtensions.cs => A-vs-An/WikipediaAvsAnTrieExtractor/SimplifyExtension.cs
Normalize whitespace
Write F# dict-to-serialized represenation code.

--HG--
extra : amend_source : 38635ca4b8e453e7a52b706f8b373877174772c3