* The arrange_foo functions are now replaced with arrange_and_commit, or
with manually created transactions and arrange_windows x2.
* The arrange functions are now only called from the highest level
functions rather than from both high level and low level functions.
* Due to the previous point, view_set_fullscreen_raw and
view_set_fullscreen are both merged into one function again.
* Floating and fullscreen are now working with transactions.
When moving focus left or right to an adjacent output, only select the
first or last child in the new workspace if the workspace's layout is
horizontalish. If it's a verticalish layout, use the last focused
container.
* 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
Replaces arrange_windows() with arrange_root(), arrange_output(),
arrange_workspace() and arrange_children_of().
Also makes fullscreen views save and restore their dimensions, which
allows it to preserve any custom resize and is also a requirement for
floating views once they are implemented.