[Orgmode] More options for org-log-done

[Wanrong Lin]

Hi,

Can/should we add more options to org-log-done, or maybe create a new 
variable org-log-state, to specify what state changes need to be logged. 
I have very fixed TODO state settings for all my org files and wish to 
avoid using in-buffer options for that. I just wonder how many people 
feel the same need as I do. Thanks for giving this a thought.

Wanrong