Fix crashes and improve performance.

Bugfix and performance improvements.

Add Sniffing Mode and Favorites.

This is a minor bugfix version.

### Feature

1. Introduce Raw Mode in composing requests, easy to copy request header from other tools to build http requests.
2. Introduce shortcut for most frequently used user-agent, content-type, and request header names.
3. Special hacks for previewing GBK encoding responses.
4. Introduce Timestamp Converter in Utilities. Meanwhile, add toolbox shortcuts in text selection in connection detail.
5. You can modify MIME Type for file form now.
6. Optimize Filter Search UI.

### Bugfix

1. Fix a sticky issue for chunked response

### Feature

1. Introduce HTTP request composer and support request replay.
2. Introduce Hosts config for f2e/mobile developers.
3. Improve form preview, support text/json/multipart/form.
4. Introduce request share, brings great convenience to QA.
5. Compatible with iPhone X and iPad MutiTask.

### Bugfix

1. Fix Issue: Some request body has no preview entry. (Only apply to new sniffing sessions)
2. Fix Issue: Save image to albums causes app crash.
3. Fix Issue: Some HTTP(s) DNS requests will fail.

- 修复 Content-Length 为 0 的时候，出现的粘包的问题
- 内存占用优化，增强稳定性