Update milestone and pre-share PlanetKit 3.2

Pre-share PlanetKit 3.2 features.

Milestone is updated. Please refer updated dates.

• Milestone

We share data session API and shared contents before release. Please check this for your implementation.

• Data session API
  • Provide reliable data send channel.
  • Application can use this as simple message sending or data streaming in whiteboard.
• Shared contents API
  • A specific value can be shared among participants in real time.
  • Provide expired time from the last modified time, which make application share time dependent contents.