Use for-keys instead of while-each

[Grinnz]

I am not sure if there is a performance reason to use each here, but otherwise, a for loop works just as well with less baggage.

[coveralls]

Coverage remained the same at 98.485% when pulling 6e4710b on Grinnz:dont_use_each into e19ae20 on dagolden:master.

[xdg]

For working code, I generally don't accept changes for personal style preferences. If there's a bug or a significant compelling reason otherwise, feel free to reopen this.