Updated Git Status Markers

The Git status markers have been updated to give more useful information about the Git status of a file in a work tree. For additions, the markers are now a plus sign: +, and coloured based on their status; red for dirty, green for added, and orange for untracked.

This release fixes an issue where the Git status of directories in a repository were not being displayed correctly, and another issue where the Git status of files in repository sub-directories were not being displayed correctly.