Grouping updates together

[bvssvni]

Sometimes multiple packages belong to the same repo, and in such cases it is desirable to group the updates together.

• Usually, external libraries depended on with higher order than an internal core library does not need update.
• External libraries with lower order does not get in the way for grouping.
• Reordering within same level does not affect grouping, but multiple packages in the same repo usually has incremental order, so naive reordering does not work.