Add Message filtering

[ethanhuang13]

In iOS 11, we can use IdentityLookup framework to filter spam message for iMessage.

The filter engine can be Core ML model or a simple white/blacklist.

To add this feature, Blahker requires major changes in:

• UI. Add tab bar to separate content blocking and message filtering
• Tutorial. Content blocking and message filtering are two very different features. Need clear guide
• README
• Release cycle. Message filtering might requires model file in app bundle

Reference:

• iMessage Spam Detection with CoreML
• 熊猫吃短信：全新的基于机器学习的垃圾短信过滤应用