notebook -- make worksheet autosave inveral configurable from notebook settings

[TimothyClemans]

Depends on #4886

CC: @wjp

Component: notebook

Issue created by migration from https://trac.sagemath.org/ticket/4887

[TimothyClemans]

Attachment: sage-4887.patch.gz

[dandrake]

comment:2

See comment:ticket:4886:3

[kcrisman]

comment:5

See #5459. This is about the worksheet autosave interval.