lavfi: add rotate filter

Based on the libavfilter SOC filter by Vitor Sessak, with the following additions:
* integer arithmetic
* bilinear interpolation
* RGB path
* configurable parametric angle, output width and height

Address trac issue #1500.

See thread:
Subject: [FFmpeg-devel] [WIP] rotate filter(s)
Date: 2010-10-03 17:35:49 GMT
tests: add filter-pixfmts-rotate test
lavfi/rotate: add angle command
require --enable-gpl for using the frei0r filter

frei0r license is GPL.

Based on a patch by Timothy Gu <timothygu99@gmail.com>.

See thread:
Subject: [FFmpeg-devel] [PATCH 1/2] LICENSE: Complete GPL'd external libraries list
Date: Thu,  6 Jun 2013 18:55:30 -0700
h264: Try parsing SPS as complete NAL in more cases

Fixes Ticket2580

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