Create group

[c-pec]

Ability to add a new group with existing contacts per ticket #72. I will have a follow up PR for tab completion of contacts name/ number, my plan is to follow this approach from the ticket:

:createGroup group name here query<Tab> lists all the contacts containing the query in the statusbar, like {+123456789 (Contact Name) | +12349876 (Other Contact Name)}. When there is only one completion left, scli inserts (+123456789) Full Contact Name.

Please let me know if you have any input on this approach.

[exquo]

Thanks!

Feel free to add the tab completion to this PR. We'll need to make sure that it works with contacts' names with spaces.

We should also add the ability to add and remove people from the group. That is pretty integral to the 'group management functionality', if we want to make it part of scli. The same signal-cli's updateGroup command can be used for that.

[c-pec]

great thanks, I'll take a look