Add command tgroup-open

open url / search in a new tab group in one command

Signed-off-by: huangyg11 <huangyg11@gmail.com>
add tgroup-open description in readme

Signed-off-by: huangyg11 <huangyg11@gmail.com>
Merge pull request #11 from huangyg11/master

Add command tgroup-open