CLN: 0.14 NDFrame cleaning
post #4324
- [ ] Fillna column wise, #4514
- [x] interpolation, consolidate Series/DataFrame interpolation to internals.Block.interpolatte, #4434, cc @TomAugspurger
- [ ] update, #3025 
- [ ] shift, #4865, #4994
- [ ] sort, #5190
- [ ] dropna API for Series, see #5234, #5250
- [ ] in place dropna , #1960 
