[bind10-dev] addZone interface for the new loadzone and zone management framework

[JINMEI Tatuya / 神明達哉]

So my specific suggestions for this sprint is:

- push #2541 and #2542 to the current sprint as they currently defined
  (modulo usual minor changes in details as we actually implement
  them)
- lower the priority of: #2440, #2441, #2500
- make sure if we RR collation in #2470 (so loading to in-memory works
  as it currently does even if we can't complete #2440/#2441)

Comments/opinions/objections?

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JINMEI, Tatuya