[Plan] Support group hosts, group vars and group combination in inventory file(hosts file)

[windvalley]

Inventory file demo:

# This is a hosts inventory file for gossh

# no group hosts
alias_name_node1 host=node1.sre.im
node100.sre.im

# hosts group
[webserver]
alias_name_node2 host=192.168.33.12 port=8022 user=vagrant password=123456 keys=~/.ssh/id_dsa,~/.ssh/id_rsa passphrase=xxx
node[06-07].sre.im port=9022 user=lisi password=654321
node08.sre.im 

# host vars for group webserver
[webserver:vars]
port=8033
user=wangwu

[dbserver]
192.168.1.10

[dbserver:vars]
user=vagrant2
password=abcdefg

# hosts group project1 has hosts that defined in group dbserver and group webserver
[project1:children]
dbserver
webserver

[windvalley]

Usage examples:

NOTE: Flag -L in above screenshot has been changed to -l.