Improve blur-edges.lua

[chermnyx]

This PR includes the following changes:

• Start blur on file-loaded event; fixes playback restore feature
• Change how the script queries video dimensions to fix hwdec (requires hwdec -copy variant or software decoding)
• Change blur filter (fixes hwdec)
• Migrate from lavfi-complex to vf property (fixes a/v desync introduced by the script)

[waverion]

You are awesome! I can't thank you enough. You significantly improved my mpv experience.

[occivink]

I like the change to not use lavfi-complex, but right now this doesn't work for videos which don't have a pixel aspect ratio of 1 (see also the sar part), they get stretched