• Re-organize menu items so that they can be accessed without switching between tabs.
• Add font size configuration in first layer setting.

• Refactor overview popup, so that it's no longer BottomSheetDialog, which shows un-necessary show/hide animations.
• Remove gray mask when overview pop up. (This is not necessary in E-ink device)
• Remove wv from useragent string, so that Google Login works.
• Modify floating action button design, so that it only outlines the button without blocking underlying content.

• Add Multi-Window support
• When adding a new tab, by default, keyboard will popup, so that users can start input the search keyword, or input the url directly.
• Heavily refactoring BrowserActivity; adopt Kotlin for better coding. Reduce BrowserActivity codes from 2500 lines to 1900 lines.