Bug fixes and class parser preparation

• fix class side override status update
• fix new method tool to not disappear in var mode
• cleanup of isAbstract implementation of Commands and other components
  • new versions of Commander and SystemCommands with same update
• some comments updated
• better warnings in pluralized form
• fix scripts defined in traits (initialize, example methods)
• better focus management for tabs
• no browser spawned when query (senders, implementors) is empty (old browser logic)
• little refactoring for class parser preparation
• remove deprecated suggestions menu from method editor to avoid confusion with new "Source code" menu. Suggestions is empty now and fix is required on Pharo side to not show empty groups
  • it was just sugsContext method removal (sadly did not found it before Pharo 7).