* Added AssetData transfer object
* Added IssueAssetTransactionData transfer object
* Reworked qora.assets.Asset into business layer object
* Reworked qora.transaction.IssueAssetTransaction into business layer object
* Added corresponding AssetRepository and support in TransactionRepository et al
* Fixed BlockChain in line with asset changes
* Some renaming inside GenesisTransaction to reflect use of transfer object, not business object
* Business transaction objects now take Repository param
* Moved HSQLDB transaction repositories into a sub-package
* Changed HSQLDBSaver.execute(Connection connection) to .execute(Repository repository) to fix visibility issues
and allow repository more control in the future if need be
* Changed from "return null" statements in HSQLDB repositories to throw DataException when an error occurs.
Better to throw than to silently return null?
* Added static version of PublicKeyAccount.verify() for when a repository-backed PublicKeyAccount is not needed
* Fixed getter/setter code template incorrectly producing "this.this.field = param"
