ThreadUI sends a recipientschange event when recipients change
changes in compose with green tests for compose_test.js

factorize hasAttachment() and use it when deciding if we should update the text value

some simplifications and send an event when segmentinfo changes

put the send button update in its own function
move enableSend functionality to compose.js
final removal of code in ThreadUI
move compose.lock calls
unit test changes
Move the messageType management to Compose
fix "integration" tests