Wallet now delegates currentAddress/freshAddress calls to KeychainGroup

This way it's possible for KCG to yield P2H addresses in future
Regenerate protobuf bindings. They didn't fully survive our refactorings.
Fixed wallettemplate to compile again after BigInteger -> Coin refactoring.
Fixed javadoc build on Java 8 by turning off the fascist DocLint.

DocLint emited errors in Orchid and Protos docs which we are unlikely to fix.
License headers are not meant to be put into JavaDocs.