vm: changes in the gas estimation

[dshulyak]

more info: https://community.spacemesh.io/t/nonce-in-self-spawn-never-ending-battle/304/4

val storageCost = tx.binarySize * STORAGE_COST_FACTOR
val baseCost = FIXED_GAS(tx.template, "Verify")
val intrinsicGas = baseCost + storageCost
val computationCost = FIXED_GAS(tx.template, tx.method)
val totalGas = intrinsicGas + computationCost

implementation

• add constant BaseGas for every template
• extend ParseOutput with BaseGas field
• header.MaxGas should be equal to BaseGas + len(tx) * STORAGE_COST + FixedGas
• change the following condition ctx.PrincipalAccount.Balance < ctx.ParseOutput.FixedGas*ctx.ParseOutput.GasPrice
  to ctx.PrincipalAccount.Balance < BaseGas + len(tx) * STORAGE_COST