Expose pure functions

[joeblau]

There are a few pure functions without side effects that are private. I'm not sure why, but it makes building UI's a lot harder because you have to re-build the internal calculations.

Here are the list of pure functions that should be exposed

• _calculateMintReward
• _calculateStakeReward

The proposal is to copy the pattern the get function. getMintReward getStakeReward