Also implements transactional block persistence. Two issues
in the transaction processing code have been discovered that
might affect other usages such as the CALL instruction.
The main fix gets us past block 49000.
You may need to clean up your database.
* checkpoint where refactoring and calling from GST runner doesn't break anything
* 14 new GSTs pass by refactoring contract creation out of p2p/chain and using from GST test runner
* 2 of 14 new tests fail in 32-bit builds
* switch from CREATE_CONTRACT_ADDRESS to isContractCreation
* switch another CREATE_CONTRACT_ADDRESS to isContactCreation
* partly fix state_db getCode to get 20 new working GeneralStateTests; remove 2 functions which existed as workarounds; switch all remaining setBalance calls in GeneralStateTestRunner to subBalance (addBalance calls already changed)
* two of the 20 new tests don't work in 32-bit builds
* fix 32-bit issue in AppVeyor
* allow another dozen or so GeneralStateTest fixtures which work on 64-bit, but not on 32-bit platforms, to safely-fail, but demarcate them separately to facilitate debugging
* steal fa672600eb from @coffeepots fix-int32-high-zero branch