* Introduce ChainHandlerCached which behaves like the old ChainHandler. Now Chainhandler.getBestBlockHeader() will read headers from the database
* Remove ChainHandler.blockchains field, now it's only available in ChainHandlerCached
* De-futurify ChainHandler.fromDatabase()
* Adjust logging
* Patch test case
* Use BlockHeaderDAO.chainTips when getting best header rather thean BlockHeaderDAO.getBlockchains(). Implement a helper method ChainHandler.toChainHandlerCached()
* Fix chain.md,wallet.md
* Make ChainHandler.getBestBlockHeader() consider time of header if chainwork is the same. Make test cases less strict on what header is the best header when both chainwork and time are the same on the eader
* Only execute callbacks on headers that are going to be created in the database, not all headers passed into ChainHandler.processHeadersWithChains()
* Turn up log level again
* Small optimizations, check if we have seen a header before before processing it in ChainHandler.processHeadersWithChains(). Fix FilterSyncMarker.toString(). Use ChainHandlerCached in Node
* Remove ChainHandlerCached in appServer, re-add it in Node.scala
* Make aesPassword option for wallet config
* Add to docs
* Make AesPassword optional
* Small touchups
* Fix for oracle server
* Fix docs
* Increase code coverage
* Bump Scala versions
Support Scala 2.12.9
and 2.13.0.
To make this easier, we delete the `scripts` project. Everything
that was in here was covered by content on the website. We also
delete the `doc` folder, as that was a remnant from when `scripts`
was called `doc`.
* Crib uPickle akka-http support while we wait for publish
* Fix compiler warnings
* Add note on test logging to contribution guide
* Reduce duplication in Blockchain implementation
* Use Scala 2.12 for website
* Introduce compat package object for collections converters
* Fix Either compiler warnings
* Add sync-chain and create-wallet docs from deleted scripts
* Fix rebase goofup
