* Added RFC for truncated block history coordination
* Clarified minimum block retention
* Added hard checks on block retention and snapshot interval, and made some minor tweaks
* Genesis parameters are immutable
* Use local config for snapshot interval
* Reordered parameter descriptions
* Clarified local config option for snapshot-interval
* rewrite for ABCI commit response
* Renamed RFC
* add block retention diagram
* Removed retain_blocks table
* fix image numbers
* resolved open questions
* image quality