ℓIP: Reduce the P-ratio from 450 to 400

Proposal:

P-ratio to build / claim rewards : reduce from 450 → 400

Allow users to claim rewards and build ℓUSD at a lower P-ratio (400), thus increasing the amount of ℓUSD in circulation.

All other aspects related to the P-ratio remain as is.

Conclusion:

This proposal is yet another step in further reducing the P-ratio, while ensuring the overall healthiness and long term growth of the platform. A reduction would allow a greater number of users to claim weekly rewards and build more ℓUSD for any given dollar amount of $LINA.