* partially done alternate migration scheme
* finish altering migration framework
* migrate tests to new migration framework
* address comments
* remove superfluous newline
[ci skip]
* TempIdx -> TempIndex
[ci skip]
* modify account_db to work on address hash, not address
* add a database migration for new accountdb
* preserve first 96 bits of keys when combining
* handle metadata keys in migration and preserve first 96 bits
* fix comments and hash address instead of hash
* different migrations based on pruning
* migrations mutably borrow self
* batch abstraction for migration
* added missing licence headers
* overlay recent v7 migration
* better error handling, migrate version key as well
* fix migration tests
* commit final batch and migrate journaled insertions
* two passes on journal to migrate all possible deleted keys
* use bloomchain crate in blockchain module. remove obsole chainfilter submodule
* update database version to 6.0
* removed redundant line
* simple db migration
* make migration slightly more functional
* bloomchain migration
* migration version is just a single unsigned integer
* updated migration v6
* parity migration
* db migration
* removed hardcoded migration dir
* replace ptr::copy with clone_from_slice, removed potential endianess problem from trace/db.rs
* removed superfluous line
* blockchains log blooms config is not exposed any more
