Merge PR #753 from oceanprotocol/feature/update_template3 into test/dt3

Changes:
- rail every blockNum function args to slot, instead of revert
- payout function never reverts
- renamed to ERC20Template3
- events are storing slot, it will be easier to group it in subgraph
- truval_submitted it's an enum now, instead of bool
- removed external addMinter function
- refactor soonest_block_to_predict  (there is blockNo diff between get and actual prediction block)
 - added SettingChanged event