Whitespace change detection and handling

[scottgonzalez]

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I wonder if the default behavior should try to detect whitespace changes that are only relevant because of a new block being introduced. For example https://github.com/scottgonzalez/jquery-ui/commit/693f6807c28b4636e0b985c144e15f1370ed0063 vs https://github.com/scottgonzalez/jquery-ui/commit/693f6807c28b4636e0b985c144e15f1370ed0063?w=1.

With the CST diff, we'd already know that the only thing that changed inside the new conditional is the leading whitespace for each line, so the diff would already be better. But it might be nice to skip over that part of the diff, or maybe just insert a symbol to indicate that the whitespace changed without actually having insertion/deletion marks for the whole block.