v2.0.0

What's changed:

The mechanism for burning tokens has been rethought. Instead of burning incrementally based on the minting date, tokens now begin to gradually "evaporate" if the user does not claim them within a certain time.

Deployment tx: https://explorer.mainnet.near.org/transactions/HMNDFJJxPyciJF6KLyjj2Jn1PJMN8MeBw4mJ9sFSNW9u