PERFORMANCE: Lucene.Net.Facet.Taxonomy.WriterCache.CharBlockArray: Compare equality and calculate hash code without allocating

[NightOwl888]

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Summary of the changes (Less than 80 chars)

PERFORMANCE: Lucene.Net.Facet.Taxonomy.WriterCache.CharBlockArray: Compare equality and calculate hash code without allocating

Description

The equality and hash code generation in Lucene relied on Subsequence() to generate the hash code and check for equality. Subsequence always allocates. The prior implementation of equality was actually copying the characters to a StringBuilder (which allocates), then calling StringBuilder.ToString() (which allocates), then comparing using String.Equals(), which only accepts a string.

This has been modified to pass startIndex and length to the CharBlockArray when calculating hash code and comparing for binary string equality. These checks are done in CharBlockArray itself on the original data structure rather than copying characters out to a buffer compare them.