move confirm block count to the start_block call, make tester track its own watermarks the same way any producer plugin would, fix off-by-one caused by not accounting for a block confirming itself; fix off-by-one caused by propagating the value of dpos-lib before it was updated; decoupled dpos-lib from bft-lib though controller still returns the max of them

explicitly remove implicit calls

route all pushes through producer

fixed producer plugin and changed some logic to respect the notion that we "called our shot" in start_block and should no longer be concerned with other time slots

move the deferred limit to the producer plugin which now controls it; route all new blocks through producer so it can maintain invariant that there is always a pending block (whether for speculative execution or future signing); re-apply unapplied transactions and apply deferred transactions on a new block (NOTE: this needs proper throttling once subjective failures are handled correctly inside controller).  Remove spurious calls to start_block in other plugins

remove explicit calls to abort/start_block in favor of asserting that there is/is-not a pending block when it is expected

Token tests

Currency tests

Cleanup, bug fixes, discounted billing, and progress towards better handling of soft failures

1. transfers are now prevented where from/to are same
2. inline transfers to self are now skipped (eosio staking for others)
3. unit test updated to demonstrate staking works

cleanup of transaction_context, throwing soft resource limit exceptions if limit is due to block, and preferential network billing of prunable data (#2000)

Move deadline specification to chain_plugin