Revert support for ugoira's thumbnail #138

Revert 30417ebec47af95519e8146de3e02ac879514431
       811af72266455d34a7225e5d34c855052a5e74ef
       b3078548de86bf32f78f73d1dca15132873615fd

Tombfix needs to reimplement this feature.
This implementation is old, and has some bugs.