modified git-lg, added git-df
modified git-lg, added git-df

- git lg
    Browse git log, and
        (Ctrl-y) copy commit hash to clipboard via macOS pbcopy
        (Ctrl-o) show commit
        (Enter) print commit hash

- git df
    git diff --color=always | diff-so-fancy

dongminkim/dotfiles,dongminkim/dotfiles