lib.exp.featx - new flow

[speed-of-light]

Create new flow of feats finder, because original feats is too hard to track problems, and hard to use. ex: #64

New API

• [x] set_algorithm

  provide a way to assign the algorithm to use.

• [x] save_feats (non public)

  save specific feats by given frame id or slide id

• [x] load_feats

  load specific feats by given frame id or slide id

• [x] make_feats

  Create all features needed, which are frames and slides under the same dataset. This is long term job, so take notify into this.