decode html entities in embedded media urls

this fixes a bug which caused some embedded media thumbnails to not
load, because of malformed requests. closes #10.
fixed opacity transition bug

a css transition wasn't applied to an opacity layer on treenodes,
resulting in a jarring flash before the fade on hover. this is now
fixed.
Merge pull request #11 from c0z3n/gordos-working-branch

Another quick merge before attacking color manipulation