Fix terminology
Update remote refs
Update head
Fix ref string convention
Reference stdio by TextReader/TextWriter
Refactor CommandIO
Implement InputReaderStub
Extract config entries from code
Re-organize Account.cs
Extract AccountImpl class for stub
FakeImapClient
Extract StubUtil class
Use folder as mailbox stub
Implement fake list mailboxes
Implement fake search
Implement read message from file
Implement store message to file
Implement delete file message