Added /addresses/proxying to find proxy forging mappings.
Added /addresses/proxykey/{genprivkey}/{recipientpubkey} to calculate proxy private key.
New Block.regenerate factory method to create new Blocks
but without having to reprocess ATs, etc.
Added support for proxied generator in Block.calcGeneratorsTarget
BlockGenerator now generates and checks new blocks for various generators,
including proxy generators.
BlockGenerator now uses generator private keys supplied by Settings.
Corresponding changes to Settings to load base58-encoded private keys.
+ minor stuff
c9035edd2c