Refactoring Cursor and Index format

[anarcher]

With #765 , We can make more readable and global fixed ordering. (Not created time from each node, Block height is timed, confirmed only order).
IMHO, the Current cursor has two parts: {prefix}/{order}. I think we can define that the delimiter between prefix and order can be /. And part delimiter can be -.
For example, All operations of a account index can represent with {account}/{block_height}-{txindex}-{opindex}. So we use the order part for the cursor: 100-3-1.

What do you think about it? @spikeekips @kfangw @Charleslee522 @Geod24 @outsideris