Math in Handlebars expressions

Hi! First of all, thanks for Ghost. Trying it our for the first time and it looks great.

Now, the issue I’m facing. I want to iterate over half a collection i.e. while index <= length / 2. But I can’t figure out how to do it. Math expressions do not work inside the mustaches.
It seems that I’ll be able to do it if I register custom Handlebars extension. But that would require me changing stuff in the core of Ghost which is non-extensible meaning I’d basically end up with a forked distribution. And that I’d like to avoid:)

Maybe you guys have some ideas of a cleaner way to do it? Or, if this is not possible at the moment, maybe I can prepare a PR which adds math expressions to Ghost?