Wrote tests for btcutils package
Expanded btcutils tests
Moved standardness multisig warning to stdout from btcutils to address.go to keep btcutils as a library without output to user.
Moved compareError to separate testutils package to use across tests in various pkgs, created multisig test but must resolve secp256k1 testing error first to uncomment
Full set of tests for btcutils pkg finished
Full suite of tests for multisig package implemented