* Add and use lenient_strcat and lenient_strncat functions
* Rename `concatenate_child_titles` function as that's no longer what it
does
* Rename `container_notify_child_title_changed` because we only need to
notify that the tree structure has changed, not titles
* Don't notify parents when a child changes its title
* Update ancestor titles when changing a container's layout
* Eg. create nested tabs and change the inner container to stacking
* No need to store tree presentation in both container->name and
formatted_title
This adds quotes around multiword arguments before they are passed to
`/bin/sh -c` in an exec command.
Example:
I connect to irc like this:
exec termite -e "mosh server tmux a"
Without this patch the arguments are passed to sh as:
termite -e mosh server tmux a
When it should be:
termite -e "mosh server tmux a"
For the command to work.
