playlist/youtube.lua: Improve patterns
playlist/youtube.lua: Improve patterns

Use more strict pattern with URL paths. Add a pattern for URL query
element. This script will no longer accept URLs that are clearly media
URLs, not playlist URLs, e.g.:
  http://www.youtube.com/watch?v=...&list=...&index=1

Signed-off-by: Toni Gundogdu <eac2284b3c43676907b96f08de9d3d52d5df0361@gmail.com>

alech/libquvi-scripts,legatvs/libquvi-scripts,legatvs/libquvi-scripts,alech/libquvi-scripts