Add more heuristic on inserting matching paren/char/end

[mrexox]

• It is not very useful to insert ]'|"} when typing ['|"{ and there's matching one on current line
• It is not useful to insert end when editing a block with end (rewriting do for example)

when I press Enter after a do |...| the end keyword is added automatically. It's not so expected. What about checking it it is needed?