v0.3.3-build1

Test build for:

• Added manual config of IMAP/SMTP auth mech
• Added digest auth for contacts and calendars - #313
• Fixed IMAP/SMTP auto auth mech - #365
• Fixed glitch when rapid deleting messages
• Refactored to engine-level serialization
• Improved toast notification logic - #115
• Added states to fix unwanted message list reset - #348
• Improved CalDAV discovery - #363