* Only allow to start interactive rebase from merged commit in current branch
* The order of commits in the interactive rebase window is as same as it's in histories page.
* Unlike anthor git frontend app `Fork`, you should edit the final message on the last commit rather than the previous commit that will be meld into while squashing commits
* replace icon with common whitespace icon in other editors
* button tooltip translations
* rename `_showHiddenSymbols` to `_showHiddenSymbolsInDiffView` to make its usage clear
* change the order of this button
* avoid highlight trailing ellipsis
* use WidthIncludingTrailingWhitespace instead of Width to keep original white space in translation
* add same modification on zh_CN and zh_TW
