Code folding fix

- reversed the collapsed/expanded icons since they were backwards.
- made the collapsed icon yellow and brighter so folded code is more
noticeable.
- updated folder icons to retina versions
Revert "Code folding fix"

This reverts commit 967f88af394ffb5f39a460d42be2d6730f321975.
Code Folding Fix

- reversed the collapsed/expanded icons since they were backwards.
- made the collapsed icon yellow and brighter so folded code is more
noticeable.
- updated folder icons to retina versions
Merge pull request #11 from jbarraud/master

Fixed yo folding icons son.