disable rpc by default.
Merge branch 'master' of https://github.com/bit-c/bitc
add testnet support: --testnet or -T

Support for testnet-style addresses is still missing.
logfile for testnet.
do not file_sync header file.
from Josselin: correctly handle invalid option
fix ASSERT in _get_block_timestamp.

If the block we're looking up in not in hash_blk, it may be in hash_orphans.
do not store all keys in config, only the non-default ones.