Binary search is a fast method to sort for an item within
a sorted list. We have a sorted list, so we can take advantage
of binary search instead of having a linear traversal through
the list.
Because binary search requires a sorted list, we need to use
the same logic for sorting and searching. Here we factor out
the filename comparison logic into `util::compare_by_name()`.
In the future we may want to have a module for sorting algorithm
logic and checking what sorting algortihm Nautilus uses.
This commit adds directory navigation to Image Viewer.
Currently it only sorts images by name, instead of following
directory sorting like the mockups.
