HORNET-0.5.4

Changed

- use iota.go/curl and iota.go/curl/bct instead of the much less performant hive.go versions
- migrate batchhasher from hive.go into hornet
- optimize batchhasher and add testcases
- iota.go now ignores 243rd trit in signature fragments

Fixed

- coordinator startup race condition
- improve tryte distribution of tools/rand-seed
- do not change default GOMAXPROCS value
- several CLI flag problems
- delete invalid milestones (2272660, 2272661) that could not be solidified after COO crashed