remove missing terminator error
make awall and send available
add bufr and advance dptr after certain ops
improve bootstrap script

the bootstrap script can now process two types of input:
run script requests and create wallet requests.
run script allows anyone to run an arbitrary script on the
bootstrap. Create wallet creates a new wallet with the provided
WalletID and an initial balance of 100.
longer opcode names
add check for bad opcode
add support for multiple buffers
add signature verification
implement gob encoding for SignedMessages
Merge pull request #142 from lukechampine/scripting

Scripting/bootstrap improvements