[AndyB] Edit limit 1.1

Allows extending edit time limit for thread author.

This add-on is very useful to allow thread authors to edit any of their posts in a thread they created for an extended period of time.

(Example of Edit limit link)



(Example of Edit limit overlay)




(Example of Edit limit overlay if edit limit is set)



(Example of User group permissions)



Features:
All phrases start with editlimit_ for your convenience.

Table modifications:
A field called andy_edit_limit is added to the xf_thread table.