1. Configure with --enable-experimental --enable-ext-tile and run "make"
to build.
2. Run "make test" to download lightfield test data: vase10x10.yuv.
3. Run lightfield encoder to encode whole lightfield:
  examples/lightfield_encoder 1024 1024 vase10x10.yuv vase10x10.webm 10 10 5
4. Run lightfield decoder to decode a single tile:
  examples/lightfield_decoder vase10x10.webm vase_tile.yuv 10 10 3 4 5 10 5

Note: Enabled use of AOME_USE_REFERENCE(previously deprecated) for this
example.

Change-Id: I657ab6e99ba1e2d1bf99ec25a3c4686fc80bc9bb