[Improvement] Polish localizer related code

[dreamerlin]

No description provided.

[innerlee]

Please give proper warnings to help user migrate

[codecov]

Codecov Report

Merging #913 (074a409) into master (df24a04) will increase coverage by 0.02%.
The diff coverage is 52.00%.

@@            Coverage Diff             @@
##           master     #913      +/-   ##
==========================================
+ Coverage   83.51%   83.53%   +0.02%     
==========================================
  Files         132      132              
  Lines        9966    10016      +50     
  Branches     1718     1725       +7     
==========================================
+ Hits         8323     8367      +44     
- Misses       1225     1235      +10     
+ Partials      418      414       -4     

Flag	Coverage Δ
unittests	83.53% <52.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmaction/models/localizers/base.py	45.88% <36.84%> (-10.99%)	⬇️
mmaction/models/localizers/__init__.py	100.00% <100.00%> (ø)
mmaction/models/localizers/bmn.py	98.02% <100.00%> (ø)
mmaction/models/localizers/bsn.py	100.00% <100.00%> (ø)
mmaction/models/localizers/ssn.py	92.18% <100.00%> (ø)
mmaction/core/evaluation/accuracy.py	92.27% <0.00%> (-0.91%)	⬇️
mmaction/core/evaluation/eval_hooks.py	11.17% <0.00%> (-0.59%)	⬇️
mmaction/models/heads/bbox_head.py	91.47% <0.00%> (ø)
mmaction/datasets/pipelines/pose_loading.py	94.38% <0.00%> (ø)
...tion/core/evaluation/ava_evaluation/np_box_list.py	47.72% <0.00%> (ø)
... and 15 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update df24a04...074a409. Read the comment docs.

[dreamerlin]

Ping @innerlee