As per T2101, moved parseOpReturn function and corresponding unit tests to cashMethods.
This is a prerequisite for T2015.

npm start
test with an outbound normal message with a single recipient tx and message label shows cashtab message
test with an outbound normal message with a multi recipient tx and message label shows cashtab message
test with an outbound encrypted message with a single recipient tx and message label shows cashtab message
test with an inbound normal message from electrum with a single recipient tx and message label shows external message
test an outbound long message
test an outbound message with special symbols
ensure correct styling for encrypted and unencrypted messages