Maxthon 3.4.3.600 Beta

# New Features:
* Supported login Maxthon Account by Facebook and Twitter accounts
# Fixes:
* Main Frame
- Maxthon Downloader interface display problem
- Polish characters input problem in Address Bar
- Could not delete downloaded files if there were special characters in the download path
* Webkit Core
- Could not open chm file attribute links in the browser
- Some pages could not be saved as html files
- Russian spell check problem
- Some data in Magic Fill could not be deleted
* Quick Access
- Sync problem of setting background image when Split Screen
- Language display problem in some page buttons
- Could not change background images successfully sometimes