2020-10-04 Old bitCNY parameters adjustment

[abit]

Purpose:
to restore the peg of bitCNY in the long run and mitigate the issue that some debt positions' collateral is too low.

Changes:
MCR has been increased from 165% to 175%.

Current parameters:

ICR 245%
MCR 175%
MSSR 150%
MCFR (Margin call fee rate) 5%
FSO (Force settlement price offset) 2%
FSFP (Force settlement fee percent) 1%

The median feed price is 0.22 CNY/BTS.
Note: the ICR value 245% for feed price 0.22 effectively means 167% if the market price is 0.15.

Borrowing has been enabled earlier. The maximum supply is limited to 35,000,000 bitCNY.