Add tree display option

[drn]

drwxr-xr-x     - darrencheng 25 Nov 14:13 .
.rwxr-xr-x   208 darrencheng 10 Nov 19:36 ├── benchmark
drwxr-xr-x     - darrencheng 10 Nov 19:11 ├── format
.rw-r--r--  1.5k darrencheng 10 Nov 19:11 │  ├── compact.go
.rw-r--r--  4.9k darrencheng 10 Nov 19:11 │  ├── long.go
.rw-r--r--   295 darrencheng 10 Nov 14:00 │  └── root.go
drwxr-xr-x     - darrencheng  9 Nov 18:25 ├── humanize
.rw-r--r--   722 darrencheng  9 Nov 20:43 │  └── bytes.go
drwxr-xr-x     - darrencheng  6 Sep 21:20 ├── icon
.rw-r--r--  5.3k darrencheng 10 Nov 13:56 │  ├── files.go
.rw-r--r--   884 darrencheng  7 Sep  7:52 │  └── folders.go
drwxr-xr-x     - darrencheng  9 Nov 19:04 ├── list
.rw-r--r--   674 darrencheng 10 Nov 18:45 │  └── root.go
.rw-r--r--  1.2k darrencheng 23 Nov 23:30 ├── main.go
drwxr-xr-x     - darrencheng  9 Nov 22:28 ├── node
.rw-r--r--  1.2k darrencheng 10 Nov 18:31 │  └── root.go
.rw-r--r--  2.1k darrencheng 25 Nov 14:13 ├── README.md
.rw-r--r--@ 767k darrencheng 10 Nov 14:28 ├── screenshot.png
drwxr-xr-x     - darrencheng  9 Nov 21:29 └── util
.rw-r--r--  1.2k darrencheng 10 Nov 14:04    └── root.go