Do not open or close branches after doc settings

Do not open or close branches after doc settings

When applying or saving Document Settings, LyX no longer opens or
closes branch insets. The intent of the previous code was to open
branch insets of a branch that is activated, and close branch insets
of a branch that is deactivated.

After some discussion [1], it was decided that the behavior intended
by the previous code was inconsistent with activating/deactivating a
branch in the context-menu of a branch inset, and the previous code
assumed a workflow of the user, rather than letting the user
separate opening/closing branch insets from activating/deactivating
them.

This commit modifies fd6cd728.

[1] https://www.mail-archive.com/search?l=mid&q=20161030220813.3zlp3zgqgomhx35y%40steph