staking on particles

• allow neuron to stake on particles and gain rewards
• staking
  • default is to stake on all particles made by neuron
  • optional parameter: choose particle for staking
• on staking neuron receives tokens in pool
  • no time bounds
  • one pool for all particles
• any time neuron can unstake from particle
• the pool collect fee from moving $A
• any time neuron can collect rewards by burning pool tokens
• effect is cyberank computation is based only on staking balances not liquid
• proposed mechanism enable a lot of use cases related to custom weighting