Bug Fixes

• Editor
  • Fix smart table bugs;
  • Fix improper leading line space on macOS;
• Fix bug which will open two tabs for the same file;
• Add copy button to copy code block in read mode;
• PluatUML: use shell to launch Java;
• Use qt 5.12.1 on macOS for better performance;
• Add theme v_simple provided by user LuoshuiTianyi;
• Support adding sibling folder in context menu;