EPIC: new iavl library is not implemented

[yihuang]

Implement the ideas described here.

• [x] #877
• [x] #890
• [X] #924
• [X] #941
• [x] #951
• [x] #948
• [x] #947
• [x] #960
• [x] #961
• [x] #976
• [x] #964
• [x] #977
• [ ] #980
• [x] #938
• [x] #981
• [x] #982
• [ ] #923
• [ ] #988
• [x] #1007
• [x] #1009
• [x] #1016
• [ ] #1017
• [x] #1055
• [x] #1067
• [x] #1089