When setting fullscreen on a hidden scratchpad container, there was a
check to see if there was an existing fullscreen container on the
workspace so it could be fullscreen disabled first. Since the workspace
is NULL, it would cause a SIGSEGV. This adds a NULL check to avoid the
crash.
This also changes the behavior of how fullscreen is handled when adding
a container to the scratchpad or changing visibility of a scratchpad
container to match i3's. The behavior is as follows:
- When adding a container to the scratchpad or hiding a container back
into the scratchpad, there is an implicit fullscreen disable
- When setting fullscreen on a container that is hidden in the
scratchpad, it will be fullscreen when shown (and fullscreen disabled
when hidden as stated above)
- When setting fullscreen global on a container that is hidden in the
scratchpad, it will be shown immediately as fullscreen global. The
container is not moved to a workspace and remains in the
scratchpad. The container will be visible until fullscreen disabled
or killed. Since the container is in the scratchpad, running
`scratchpad show` or `move container to scratchpad` will have no
effect
This also changes `container_replace` to transfer fullscreen and
scratchpad status.