New variable request: org-archive-todo-only

[Wanrong Lin <wanrong.lin@gmail.com>]

Hi,

In my org file I have a mix of "actionable" items (TODO items) and 
informative items (notes, references and etc). Normally I only archive 
TODO items when they are done, and don't archive informative items 
(since most of them have some long-term value). So, can we add a new 
variable to "org-archive-todo-only" to control the behavior of following 
functions:

1. org-archive-subtree
     1) when org-archive-todo-only is nil, behave as it does now, with a 
little bit modification:
           - if the current heading is a TODO item and 
org-archive-mark-done is nil, check whether it is in a "DONE" state. If 
not, prompt for user confirmation.
     2) when org-archive-todo-only is t, if the current heading is a 
TODO item, behaves the same as 1). if the current heading is NOT a TODO 
item, prompt for user confirmation.

2. org-archive-all-done
     1) when org-archive-todo-only is nil, behaves as it does now
     2) when org-archive-todo-only is t, only checks the headings that 
are a TODO item.

Without the change to those functions, I have to be very careful not 
archiving something I don't want to.

I put in an advice by myself to change the org-archive-subtree behavior 
as above, but I can not do it with function org-archive-all-done. And I 
also think this may be an improvement that makes sense for many people, 
hence the proposal/request.

Thanks a lot for comments and consideration of the above.

Wanrong