Handle Xcode code placeholders.
Merge branch 'jgross-xcode-placeholders' of https://github.com/JoshuaGross/uncrustify into JoshuaGross-jgross-xcode-placeholders

Conflicts:
	tests/objective-c.test
Drop new option dont_protect_xcode_code_placeholders

I don't see how anyone would not want this.
Rework parse_code_placeholder()