Handle Xcode code placeholders.

If you uncrustify while editing a file in Xcode (which I very frequently do), any code placeholders inserted by Xcode will be mangled. This commit fixes that.

I'm very open to changing the option or removing it (`<#` and `#>` don't appear to conflict with anything in any other language). Is there a way to have a boolean option set to `true` by default?