2021-09-27 bitCNY price feed parameters tuning

[abit]

2021-09-27 bitCNY minimum_feeds adjusted from 3 to 1, feed producers list adjusted to [ in.abit, btspp-witness ] temporarily.

Reason:
The other price feeder producers need time to adjust their price feed scripts to correctly feed bitCNY price.

Current parameters:

ICR (Initial collateral ratio) 300%
MCR (Maintenance collateral ratio) 160%
MSSR (Maximum short-squeeze ratio) 105%
MCFR (Margin call fee rate) 3%
FSFP (Force settlement fee percent) 3%
FSO (Force settlement price offset) 2%
Force settlement delay 24 hour
Maximum force settlement volume per hour 0.5%
Minimum feeds 1
Price feed producers list:
1.2.35248   in.abit
1.2.1031601 btspp-witness

Borrowing is enabled. The maximum supply is limited to 30,000,000 bitCNY.
Force-settlement is disabled.