Streamlined Staking Implementation

[achimstruve]

I implemented a more streamlined and consolidated staking experience in the latest QTM spreadsheet version as follows:

• Removed the fixed APR staking option completely as I don't see any useful applications
• Instead of the previous 3 staking approaches in the QTM (fixed APR, vesting, buyback & distribute), we have only one now: Once the staking vesting reward bucket runs out of tokens, the buyback and distribute will automatically be activated.
• Also one can set a mint / burn ratio that will automatically mint tokens and distribute them to stakers based on burnt tokens in the economy. This is a complementary or replacing reward mechanism to the second point. Setting this value to 0 disables any minting automatically.

I want to get these changes also reflected/implemented in our radCAD QTM version.

Is there someone who is interested actually doing the implementations? It is a great exercise to get your hands dirty on the model. I want this to be done by end of next week. Let me know until EOD today, if you are interested in this. You would get the corresponding new QTM spreadsheet as a template.
Otherwise I'll just do it.

[achimstruve]

Finished and tested this implementation with this commit. Also all UI related aspects have been adjusted accordingly.