Enhanced Commenting Support (simpleNote)

Hi all,

I had an action item to revisit the feature "Enhanced Commenting Support" (https://wiki.oasis-open.org/xliff/XLIFF2.0/Feature/EnhancedCommentingSupport) to see if it could be considered done or not. 

I propose two changes to the current <simpleNote> element:

a) Add an optional id attribute. This will allow the use of the note with inline annotation as described in section "2.6.3.1.3 Comment Annotation".

b) Rename <simpleNote> to <note> because there is no other note in the core and we should use simple name when we can.

Cheers,
-yves