Provide shortcuts for recurring modifications

[dbitouze]

When a user, or a moderator, edits a question or an answer, he often does the same kind of modifications:

• fix typos,
• add code snippets markup,
• minor changes,
• correct markdown syntax errors or clumsiness,
• add some precisions,
• improve layout,
• etc.

It is painful to have to write specific text as modifications' summary, each time such recurring modifications occur. It could be nice to be able to use shortcuts for providing automatic, "pre-written", modifications' summary that may tuned before being sent.