update install script

Signed-off-by: Wang Zhen <yuchen12@gmail.com>
add update-tmux-files.sh

Signed-off-by: Wang Zhen <yuchen12@gmail.com>
add update-dircolor.sh

Signed-off-by: Wang Zhen <yuchen12@gmail.com>
update dircolors.256dark: 2013-05-03

Signed-off-by: Wang Zhen <yuchen12@gmail.com>