Added support for mulit-line endpoint descriptions via blank
intermediate lines in php controller method docblocks.
Also tweaks endpoint header design for better flexing and alignment.
Provides a way for users to actually delte their user drafts where
required.
For #3927
Added test to cover new endpoint.
Makes update to MD editor #setText so that new selection is within new
range, otherwise it errors and fails operation.
Ensures some sensible text is always in webhook text data.
Also aligned some notification reporting to use centralised activity
system instead of custom success events.
For #4216
