Upon parsing an invalid OP_PUSHDATA, append the invalid opcode to already parsed valid opcodes

On invalid OP_PUSHDATA, clear the added chunks.

test case for above changes
clean up address and script types

this makes for consistent naming of the address/script types everywhere,
gives us some more flexibility to introduce new types,
makes #encode/decode_address more generic and
highlights the importance of carrying the address type along the hash160,
while still preserving the old APIs for compatibility
clean up network descriptions
fix block builder target comparison
fix regtest proof_of_work_limit
tx builder: option to add extra fee on top of the calculated minimum fee
key regenerates pubkey after setting privkey
minor fix in CommandClient
Script #get_keys_provided for multisig scripts
script: leave nil object when address cannot be decoded from pubkey
Remove 'rescue Exception'