Vote-/UTXO-layer and branch unit tests (#430)

* Feat: initial commit

* Feat: added setPreferred to TransactionMetadata

* Feat: added a Conflicting() method to the transactionMetadata

* Fix: fixed logic bug

* Feat: refactored fcob

* Refactor: refactored additional code

* Fix: fixed a bug in ForeachConsumers

* Refactor: cleaned up code

* Feat: implemented FCOB consensus into the valuetransfer dapp

* Refactor: refactored FCOB

* Docs: added some additional comments

* Docs: fixed comments

* add branch manager conflict test

* cleans failing test

* Refactor: commit before branch change

* Fix: fixed bug in AggregateBranches

* assert aggr. branch IDs

* expands branch conflict detection test

* add visualisation of branch graph of test

* Feat: added PayloadLiked Event

* Refactor: fixed some missing comments + added liked to marshal

* Feat: reworked the preferred and liked propagation

* Refactor: cleaned up some logic

* Refactor: simplified code

* Refactor: cleaned up more stuff :P

* Refactor: refactor

* Feat: moved test + refactored fcob

* adds more tests

* fixes liked state not getting updated correctly of conflict members

* adds additional liked/preferred propagation test

* Fix: fixed missing preferred propagation to aggregated branches

* Fix: fixed a few bugs in liked propagation

* adapt to new hive.go version

* upgrade hive.go

* Feat: started implementing a wallet

* Feat: extended wallet files

* remove weird test

* use mem db for tests

* more tests

* did someone say more tests?

* Fix: fixed bug in findDeepestCommonDescendants

* simply test

* adds additional test

* use store backed sequence

* add option to use in-memory database

* address review comments

* Fix: fixed missing events in branchmanaer

* Feat: propagate changes from branch to transaction

* Feat: started implementing confirmed propagation

* Fix: fixed unreachable code

* Refactor: refactored some code according to wolfgangs review

* Refactor: cleaned up the code according to DRY

* Refactor: refactored according to wollac

* Refactor: refactored according to wollac

* Refactor: refactored according to wollac

* Refactor: refactored the code to make it more readable

* Refactor: added some doc comments + cleaned up some more code

* fix weird duplicated code

* fixes shadow dec.

* check modified flags

Co-authored-by: Hans Moog <hm@mkjc.net>
Co-authored-by: Wolfgang Welz <welzwo@gmail.com>