vf_unsharp: switch to an AVOptions-based system.
Merge commit 'b83e9efc53e5491716625aa31c69006b1119b280'

* commit 'b83e9efc53e5491716625aa31c69006b1119b280':
  vf_unsharp: switch to an AVOptions-based system.

Conflicts:
	doc/filters.texi
	libavfilter/vf_unsharp.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>