qvm_ls.py : add template tree mode

[RandyTheOtter]

Add template tree mode (-T), because I like it.

Almost exactly as network tree, but returns tree of templates, i.e.:

NAME                             STATE    CLASS         LABEL   TEMPLATE                 NETVM
sys-tmpl                         Halted   TemplateVM    black   -                        -
└─sys-net                        Running  AppVM         red     sys-tmpl                 -
└─sys-dvm                        Halted   AppVM         red     sys-tmpl                 sys-firewall
  └─sys-usb                      Running  DispVM        red     sys-dvm                  -
  └─sys-firewall                 Running  DispVM        green   sys-dvm                  sys-net

This is by no means complete, I pretty much just crammed my code the same way sort_to_tree is integrated into the program.

To do:

• Edit manual once we agree on UX

Maybe do, if people want it:

• Choose a good exception for the while loop getting stuck / somehow get rid of the while loop
• Find a better way to integrate this functionality. Having multiple tree "modes" seems more logical than two separate tree-producing functions.
• UX: What flag should be used, and how? Again, maybe something similar to --tree TYPE is a better choice than --tree and --ttree?

What I would personally like to do, but probably won't get there:

• Make better tree-drawing algorithm, this one isn't very comprehensible. Programs like tree do it better.

I don't have a dev setup, so no testing with main or release4.3 can be done by me, but similar change to 4.2 version of qvm_ls.py works.
(Is there a way to somehow install these packages over 4.2 stuff without breaking anything?)

Also, I've noticed that sort_to_tree says that it returns a list of sets, which isn't true, it returns a list of tuples.