Rename type to class internally

There has been some discussion about us conflating types and classes:

<blockquote class="twitter-tweet" lang="en"><p><a href="https://twitter.com/myronmarston">@myronmarston</a> <a href="https://twitter.com/JonRowe">@JonRowe</a> [1/?] I noticed RSpec seems to conflate Ruby&#39;s classes with types, in both the docs (<a href="http://t.co/rkyTrIIOSh">http://t.co/rkyTrIIOSh</a>) and the</p>&mdash; friendly catduck™ (@duckinator) <a href="https://twitter.com/duckinator/status/542148488365371392">December 9, 2014</a></blockquote>
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<blockquote class="twitter-tweet" lang="en"><p><a href="https://twitter.com/myronmarston">@myronmarston</a> <a href="https://twitter.com/JonRowe">@JonRowe</a> [2/?] various codebases (<a href="https://t.co/jamOJhnIpp">https://t.co/jamOJhnIpp</a>). I&#39;d be willing to fix that if you all are interested; but, if you</p>&mdash; friendly catduck™ (@duckinator) <a href="https://twitter.com/duckinator/status/542148638399807488">December 9, 2014</a></blockquote>
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<blockquote class="twitter-tweet" lang="en"><p><a href="https://twitter.com/myronmarston">@myronmarston</a> <a href="https://twitter.com/JonRowe">@JonRowe</a> [3/3] are, how would you want me to approach the code side of it? Are their exposed APIs that this would break?</p>&mdash; friendly catduck™ (@duckinator) <a href="https://twitter.com/duckinator/status/542148817219756032">December 9, 2014</a></blockquote>
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Now I disagree that the matcher is incorrectly named (as it's a documentation heading only) but these changes are distinctly classes (and not sample data referring to type either) so I saw no harm in making them.

/cc @duckinator