Implement support for big files and Markdown preview#4576

TranceLove wants to merge 2 commits intoTeamAmaze:release/4.0TeamAmaze/AmazeFileManager:release/4.0from

TranceLove:feature/text-editor-big-file-markdownTranceLove/AmazeFileManager:feature/text-editor-big-file-markdownCopy head branch name to clipboard