Index builder and explorer sources

Requires buildchain.conf : rpc-user|rpc-ww|*|e-Mail-address|servername

Data-root is hard-coded ($root=....)
Port 21015 is hard-coded (e-Gulden blockchain)
Trust is hard-coded at 4 blocks
Index-builder typically runs with the block-building frequency (2
minutes for e-Gulden)