Fix crashes when dragging and dropping files outside of the gamelist
VideoCommon: remove unused stats
Statistics: Reformat stats string
AVIDump: cleanup
AVIDump: update ffmpeg/libav API usage

libav 10 was released on May 10th, 2014 and it drops support for some
long-deprecated stuff like avcodec_encode_video().
CMake: remove unused/duplicate definitions
CMake: mention ffmpeg in libav messages

We support both.
CMake: update min. libav/ffmpeg library versions
AVIDump: rename frame variables
Fix OpenGL VSync
Merge pull request #537 from Armada651/master

RenderFrame: Set the background to black.
Merge pull request #533 from Anti-Ultimate/master

Fix OpenGL VSync
Merge pull request #522 from lioncash/fix-dragdrop-crash

Fix crashes when dragging and dropping files outside of the gamelist
Fix dragging and dropping savestates in the render window
Fix ISO Directory extraction.
DiscIO: Fix extra tabs in the banner loader headers
DiscIO: Centralize the banner pointer and validity boolean into IBannerLoader

These are both used within the banner loaders, and IsValid is exactly the
same. So this makes sense.
Merge pull request #540 from lioncash/banner

Centralize some common banner loader class members.
Merge pull request #452 from degasus/stats

Video statistics update
Merge pull request #539 from jordan-woyak/fix-extract-directory

Fix ISO Directory extraction.