Improvements on deck and note insertion commands

[louietan]

It's cumbersome to move the point to the deck or group heading in order to make note insertion command insert the note skeleton at a suitable place.
It would be better to ask the user under which headline they want to insert the note, or even better to make a strategy to select the best insertion point.
Same to deck insertion command.

[louietan]

Improved in 9ef7759