allow for block producer configurable leeway for cpu and net usage during execution (still checks against new limits without the leeway at the end of the transaction)

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

- buy & sell ram using bancor algorithm
- ram is no longer delgated
- fixed warning with double secondary index
- add block_timestamp_type

- udpate system contract to set initial account bw to 0
- update system contract to process new on block header
- update cleos api and get info api

* clean up configuration parameters
* use dynamic max_inline_action_size configuration parameter to limit size of inline actions
* use dynamic max_inline_action_depth to limit recursion depth of inline actions
* change deferred_trx_expiration_window parameter into a dynamic configuration parameter
* add numerator and denominator configuration parameters for later context free data discount implementation
* bill delayed transaction for the additional net usage of the eventual retirement of the deferred transaction

Also, it now checks to ensure the proposed producer schedule would actually change the schedule.

Also update native action handlers to reflect changes in PR #2440.

singleton takes code and scope as runtime-parameters, global_state_singleton restored in system contract, hack to prevent llvm-linker from removing apply function #2227